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The planet Mars; Everything you need to know



Mars or the Red Planet is the most well-known world in the solar system, which has been the target of numerous research and missions; But there are still many questions about it.

The planet Mars; Everything you need to know

Today, we can say that Mars is one of the most familiar places in the solar system, thanks to numerous explorations and discoveries. Mars is the fourth planet in the solar system (based on distance from the Sun) and the second smallest planet after Mercury. The name Mars or Mars is inspired by the Roman god of war and is often known as the Red Planet.

Table of Contents

  • Why is Mars called the red planet?
  • How was the planet Mars formed?
  • Why is Mars smaller than Earth?
  • Physical characteristics and composition of the planet Mars
  • The internal structure of the planet Mars
  • Surface features of the planet Mars
  • Holes and craters on the planet Mars
  • Martian ice caps
  • Aquifers
  • Life on Mars
  • The atmosphere and climate of the planet Mars
  • The magnetic field of the planet Mars
  • Rotation and orbit of the planet Mars
  • Moons of Mars
  • The wonders of the planet Mars
  • land and sea
  • Channels of Mars
  • face of mars
  • Martian tree
  • The Martian
  • Gandhi’s face
  • Alpha biological station
  • Blue spider
  • Martian beetle
  • Big discharge
  • Strange green stone
  • Observations and explorations of the planet Mars
  • Perseverance mission
  • Manned missions
  • NASA
  • SpaceX
  • The impact of travel to Mars on humans

The abundance of iron oxide in the crust of Mars is the main reason for the red color of the soil. The days and seasons of Mars are similar to Earth’s to a great extent, due to the similarity of the rotation period around the Sun and its axial rotation to Earth. The largest volcanic mountain and the second highest mountain in the entire solar system is located on Mars, and Marineris Valley is one of the largest valleys in the solar system. Mars has two moons named Phobos and Deimos, which have an irregular shape, unlike Earth’s moon. Probably, these two moons were asteroids that were trapped by the gravity of Mars.

Mars is a cold planet and a desert world with a very thin atmosphere. Martian dust storms are so intense that they can cover the entire surface of the planet. The temperature of this planet is so low that the carbon dioxide in the atmosphere directly falls on its surface in the form of snow and ice.

The volume of water ice deep in the Antarctic ice cap of Mars is enough to cover the entire surface of the planet up to a depth of 11 meters. In November 2016, NASA reported findings of subsurface ice on the Utopia Panitia plate. According to estimates, the volume of water discovered is equal to the volume of water in Lake Superior of North America. Mars can be easily seen from Earth with the naked eye as a red dot.

Image of OSIRIS
This color image of Mars was captured by the OSIRIS instrument of the European Space Agency’s Rosetta spacecraft in February 2006.

Why is Mars called the red planet?

The bright copper color of Mars is due to the abundance of iron-rich minerals in its regolith. Regolith is loose rocks and dust that cover the surface. Earth’s soil is also a type of regolith, with the difference that it is rich in organic matter. According to NASA, iron minerals undergo oxidation or rusting, giving Mars its reddish appearance.

How was the planet Mars formed?

Approximately 4.6 billion years ago, in the early days of the solar system, a disk of gas and dust formed in the orbit of the young sun. Two theories show how, over millions of years, the rocky inner planets of the solar system formed from within this disk of matter. According to an older theory, the dust in the inner solar system formed into larger masses, and these masses gradually became the size of the Earth’s moon. The collision of these planetary embryos eventually led to the formation of planets such as Mercury, Venus, Earth, and Mars.

Solar nebula: a disc of dust and gas
Artist’s conceptual image of the solar nebula, a cloud of gas and dust in which the planets of the solar system formed.

However, a newer theory considers a different growth process. In this process, millimeter-sized pebbles moved towards the sun from the outer part of the solar system. Along the way, these pebbles took the form of inner planetary embryos and gradually reached their current size. Both theories are based on theoretical models and computer simulations that aim to recreate the conditions and variables of the early solar system. Both theories also describe possible pathways of planet formation; But which theory is correct? Which process actually occurred?

Unlike Earth, which is tectonically active and rocks change over billions of years, Mars has no tectonic activity; Therefore, the oldest Martian rocks are present on its surface. Studying these rocks is a way to find out how the red planet was formed. Also, scientists can answer these questions by examining extrasolar planets and their similarity to the planets of the solar system, as well as the same elements in the formation of Earth and Mars; But none of the theories have been conclusively proven yet.

Why is Mars smaller than Earth?

The size of a planet depends on the amount of matter and the initial cloud of gas and dust. According to NASA, the radius of Mars is nearly 3390 km; But Mars is not perfectly circular like Earth. Rather, due to the rotation, it has a slight bulge in the equatorial part. One of the main reasons why Mars is small compared to Earth is the difference in gravity between the two. The gravity of Mars is about one-third that of Earth because it has less mass to attract objects to its surface. This feature can be useful for research and discoveries to some extent. For example, the Ingenuity helicopter flies more easily and takes off from the surface of Mars due to lower gravity; But this gravity has its problems and makes the atmosphere of this planet very thin.

Comparison of Earth and Mars
Comparison of Earth and Mars

Physical characteristics and composition of the planet Mars

The diameter of Mars is half the diameter of the Earth and its surface area is slightly less than the land area of ​​the Earth. Mars is less dense than Earth. Its volume is 15% of the Earth’s volume and its mass is approximately 11% of the Earth’s mass; As a result, the gravity of Mars is 38% of the gravity of Earth. Therefore, a person weighing 100 kg on Earth will be 62 kg on Mars, but his mass is the same on Earth and Mars.

The internal structure of the planet Mars

The dust that covers the surface of Mars is like talcum powder. Under a layer of dust, the Martian crust is placed, most of which is made up of basalt volcanic rocks. Mars soil contains nutrients such as sodium, potassium, chloride, and magnesium. The Martian crust is thought to be one piece. Unlike Earth, the Red Planet has no tectonic plates. Tectonics or plate tectonics float on the mantle and are the main cause of the deformation of the Earth. But since there is almost no movement in the crust of Mars, the molten rocks have gathered in one place and created huge volcanoes on the surface of this planet.

Of course, this does not mean that the shell is immobile. According to researches, probably strong thrusts have led to the creation of Martian slopes. According to the researchers, ice is an important material for smoothing drifts on Mars, even in tropical areas such as Valais Marineris. Any possible life on Mars is probably going on underground. Although astronomers continue to search for signs of past and present life on Mars, no evidence of Martian life has been found so far.

According to the evidence, there has been no volcanic activity on Mars for millions of years. The mantle of Mars is very silent and calm. The mantle is composed of silicon, oxygen, iron, and magnesium, and its thickness reaches 1240 to 1880 km, according to NASA. The center of Mars has a solid core of iron, nickel, and sulfur that does not move; Therefore, this planet does not have a global magnetic field; Without the presence of a magnetic field, cosmic rays hit this planet and turn it into an uninhabitable world.

NASA’s InSight rover has been investigating the interior of Mars since 2018. InSight has measured Martian earthquakes. InSight’s data revealed key insights into the planet’s internal structure. For example, according to the new estimates of this mission, the diameter of the core of Mars is between 1780 and 2080 km and the thickness of its shell is between 24 and 72 km. The mantle forms the rest of the structure. This is while the width of the earth’s core reaches 1,220 km and its mantle reaches 2,900 km. Also, the earth has two types of crust. Continental and oceanic crust, whose thickness is equal to 40 km and 8 km, respectively.

Internal structure of Mars

Mars hosts the highest mountains and the deepest and longest valley in the entire solar system. The height of Mount Olympus reaches 27 km, which is almost three times the height of Mount Everest. The depth of the Marineris Valley of Mars is seven kilometers and its width reaches 4000 kilometers from east to west, which is almost equal to the width of Australia.

Scientists believe that the Marineris Valley was created by scratching and stretching the crust. The width of independent internal valleys reaches 100 km. The valleys merge in the central part of the Marineris Valley in an area 600 km wide. Large channels rising from the end of some valleys and layered sediments show that the valleys were once full of water. Mars has the largest volcanoes in the entire solar system, Olympus Mons being one of them. The diameter of this huge volcano reaches 600 km and is so wide that it contains the state of New Mexico.

Olympus Manes
Olympus Mons is the largest known volcano in the solar system. This image was captured by NASA’s Viking 1 orbiter.

The canals, valleys, and water passages of Mars show that in the past liquid water flowed on the surface of this planet. Some channels are 100 km wide and 2000 km long. Liquid water may be found in cracks and holes in the subsurface rocks of Mars. According to a 2018 study, the salty water beneath the surface of Mars could contain significant amounts of oxygen, which is necessary for microbial life. However, the amount of oxygen depends on both temperature and pressure; The change in the deviation of the rotation axis of Mars causes changes and temperature fluctuations.

A large part of Mars consists of low and flat plates. The northern lands of Mars are among the flattest and smoothest plates in the entire solar system, which were probably formed due to the flow of water on the surface. The surface height in the northern hemisphere of Mars is lower than in the southern hemisphere, and this means that the northern crust is thinner than the southern crust. The difference between north and south could be due to a very large collision that occurred soon after the birth of Mars.

Holes and craters on the planet Mars

The number of craters on Mars varies in different places and based on the age of the surface. A large part of the southern hemisphere of Mars is very old, as a result, there are many craters in this area, the most famous of which is Hellas Planitia with a width of 2300 km. On the other hand, the northern hemisphere of this planet is younger and has fewer craters. Some volcanoes also have a small number of craters, which indicates that they have recently erupted and the resulting lava has covered the old craters. Some craters have strange deposits of pebbles around them that look like dried mudflows, possibly indicating the presence of subsurface water or ice.

Martian ice caps

Mars has two prominent ice caps; which are in continuous darkness in polar winter and 25-30% of atmospheric carbon dioxide gas is accumulated in this part in the form of dry ice. When the poles are exposed to sunlight, the frozen carbon dioxide turns back into a gas. These seasonal processes transport a large portion of water vapor and dust, creating Earth-like snow and large cirrus clouds. 70% of the polar ice caps are water. Frozen carbon dioxide also sits in the form of a thin layer with a thickness of approximately one meter only in the winter season on the northern cap, while the thickness of dry ice on the southern cap reaches eight meters.


Due to the thin atmosphere of Mars, its surface conditions are not very favorable for water flow. For this reason, the possible sources of water are either underground or placed in the form of ice caps at the poles. According to past modeling, some of the Martian waters are underground. There are many signs of water in the impact craters; Among the canals that have grooves in their walls due to the passage of water and evidence of erosion and coastlines. As a result, craters may be a clue to underground water.

In the bed of these craters, there is evidence of the existence of water flows in the past, which have settled down over time. According to estimates, the depth of the channels corresponds to the oceans of Mars four billion years ago. Thus, the discovery of water became a prelude to the discovery of life on Mars.

The volume of water in Mars’ Valais Marineris canyon system exceeds expectations

In 2021, the FREND instrument from the Tracer Gas Orbiter (TGO) discovered subsurface water on Mars. The instrument discovered a region with an unusual amount of hydrogen in the Valles Marineris canyon system. Considering that the hydrogen element is abundant in water molecules, it seems that forty percent of the material near the surface of this region is water. This area is as rich in water as the Netherlands. This amount of water in this area, which was much more than expected, could be in the form of ice or water in the soil minerals.

In early 2022, the MRO orbiter discovered traces of water that appeared to have flowed on the surface of Mars 2-2.5 billion years ago. According to previous estimates, the surface water of Mars has evaporated about 3 billion years ago. As a result, based on this finding, the surface water of Mars has flowed on the surface of this planet for a billion years longer than the estimates.

Life on Mars

Water is the basic requirement of life. The discovery of water, especially underground liquid water, has increased the hope of discovering Martian life; But to understand the potential of Martian life, it is necessary to go back to 3-4 billion years ago. At that time, Mars and Earth had many features in common. The red planet was hot and humid, had a stable atmosphere, and was far from its current cold and unpleasant face. David Parker, European Space Agency’s Head of Robotics and Human Exploration, says:

At the beginning of its life, the raw materials of the planet Mars were similar to the materials that make up the Earth; But over time, everything changed. This process was just like a kind of collapse.

Mars lost its magnetic field over time. The loss of the magnetic field means that the planet will have no protection against harmful radiation. Mars also lost much of its atmosphere. Because the atmosphere is one of the other necessary criteria for the formation of life on the planet and provides the necessary oxygen. Parker says:

Mars still has a thin atmosphere, most of which is carbon dioxide. The reason for the extreme cold of this planet is its very thin atmosphere.

Image of Mars rover Perseverance from the surface of Mars
The Perseverance rover took this photo of the surface of Mars in January 2022. Perseverance is searching for signs of ancient life on Mars.

However, the cold and unprotected Mars did not discourage scientists from searching for signs of life on this planet. NASA’s Curiosity rover discovered organic matter on Mars in 2018. This discovery meant that the building blocks of life once existed or still exist on Mars. NASA researchers say:

Conservation of organic resources is a turning point in understanding life on Mars. Regardless of whether Mars has ancient life, its organic matter can be chemical clues to its current processes and conditions. Curiosity also discovered methane, the simplest organic molecule, on Mars. Methane can also be a clue of chemical processes on Mars.

According to the new findings of the Curiosity rover, evidence of ancient life on Mars has disappeared. The Curiosity rover made a surprising discovery by examining the clay sedimentary rocks around Gale Crater. This impact crater was once a lake that was created by an asteroid hitting the Red Planet about 3.6 billion years ago.

Clay is one of the most suitable sources for the search for evidence of life, and it is formed when the minerals in the rock are destroyed and turn red due to contact with water. Also, it is a good material for storing microbial fossils.

Curiasti sampled two ancient mudstones (a type of clay-containing sedimentary rock) from a dry riverbed, dating back to about 3.5 billion years ago, and both 400 meters apart. By examining these two samples, the researchers realized that one of the veins contained only half of the expected clay minerals. The other vein contained larger amounts of iron oxide, which is responsible for the red color of Mars.

According to researchers, seepages are the main culprit of the disappearance of ancient biological works: extremely salty and salty waters penetrating into clay layers rich in minerals make them unstable and lead to the disappearance of geological and biological works. In general, despite the many similarities between Earth and Mars, the Red Planet is not suitable for life for one simple reason. The diameter of Mars is exactly 53% of the diameter of the Earth (a little more than half); For this reason, Mars is not a suitable environment for maintaining volatile substances suitable for life, including water.

The atmosphere and climate of the planet Mars

Climate changes on Mars are extreme. The atmosphere of this planet was suitable for the flow of liquid water on the surface in the past, But today only a thin layer of it remains. The climate of Mars depends on several features such as ice caps, water vapor, and dust storms. Sometimes massive sandstorms can cover the entire planet like a blanket for months, turning its skies dusty and red. The atmosphere of Mars is 100 times thinner than the Earth’s atmosphere and 95% of it consists of carbon dioxide. According to NASA data, the atmospheric composition of Mars is :

  • Carbon dioxide: 95.32%
  • Nitrogen: 2.7 percent
  • Argon: 1.6 percent
  • Oxygen: 0.13%
  • Carbon monoxide: 0.08%
  • A small amount of water, nitrogen oxide, neon, hydrogen, deuterium, oxygen, krypton, and xenon.

Orbital images show fluvial sheets and possible vast ocean boundaries in Mars’ past. Although the Mars rovers have managed to discover evidence of limestone on the surface of Mars, there are still no clear reasons for the planet’s thin atmosphere. According to one theory, the low gravity of Mars, as well as the absence of a magnetic field, has made the atmosphere of this planet vulnerable to the pressures caused by the solar wind. Over millions of years, the pressure of these winds removed light molecules from the Martian atmosphere, thinning it. NASA’s MAVEN probe has been in charge of studying the atmosphere of Mars. According to other hypotheses, the collision with a small object may have led to the destruction of the Martian atmosphere.

The thin atmosphere of Mars and its great distance from the Sun is the reason for its very low temperature compared to Earth. The average temperature on Mars reaches minus 60 degrees Celsius. The temperature of Mars reaches minus 125 degrees Celsius near the poles and 20 degrees Celsius near the equator. Although the Martian atmosphere is much thinner than Earth’s, it is thick enough to retain weather, clouds, and winds. Huge dust storms have caused the surface of Mars to be covered with iron oxide dust. Dust is a stable part of the Martian atmosphere.

Martian clouds
A view of Martian clouds captured by the Curiosity rover

The magnetic field of the planet Mars

Mars is deprived of a global magnetic field, but solar winds produce a type of magnetosphere or magnetosphere through direct reaction with the Martian atmosphere. On the other hand, according to the findings of the InSight probe, the magnetic field at the landing site of this probe is ten times stronger than predicted and fluctuates within a few seconds to several days.

Before the InSight mission, the best estimates of the magnetic fields of Mars were obtained from satellites in the orbit of this planet, whose average distance to Mars was 150 km. Mars had a global magnetic field in the distant past. The InSight magnetic sensor provided new clues about the phenomena of the upper atmosphere and the space environment around Mars. Just like Earth, Mars is exposed to solar winds; But since it lacks a global magnetic field, its protective insulation against the sun is weaker.

According to the researchers, the fluctuations of the magnetic field of Mars during the day and night are caused by the combination of the solar wind and the interplanetary magnetic field around the planet, and the solar rays produce a magnetic field by charging the upper atmosphere and producing electric currents.

Rotation and orbit of the planet Mars

Since Mars is farther from the Sun than Earth, its year is longer than Earth. Mars completes the orbit of the Sun during 687 Earth days; Therefore, the Martian year is equal to two Earth years. The length of days on Mars and Earth is almost equal. The rotation of Mars around its axis or a Mars day is 24 hours and 40 minutes. While the earth day is 24 hours.

Like Earth, Mars has different seasons, with the difference that the Martian seasons are usually longer, because the elliptical orbit of Mars around the Sun is a little more elongated than other objects; Therefore, when Mars is at its closest distance to the Sun, its southern hemisphere faces the Sun and experiences a short and hot summer; While a short and cold winter is going on in the Northern Hemisphere. When Mars is farthest from the Sun, its northern hemisphere faces the Sun. In these conditions, a long and moderate summer will flow, while the southern hemisphere will experience a cold and long winter.

Moons of Mars

American astronomer Asaph Hall discovered two moons of Mars named Phobos and Deimos in August 1877. The HiRISE camera of the Mars Orbiter captured two images of the two largest moons of Mars, Phobos and Deimos, on March 23, 2008. Ninety-four years after Hall’s discovery, the Mariner 9 spacecraft got a better view of the two moons of Mars. The most remarkable feature of Phobos is a ten-kilometer-wide crater that is half the width of the moon itself.

The moons of Mars are among the smallest moons in the entire solar system. Phobos is only slightly larger than Deimos and is located at a distance of 6000 km from the surface of Mars. Phobos orbits Mars once every three days. The more distant moon Deimos completes an orbit of Mars every thirty hours. The rotation direction of Phobos is inward and it gets closer to Mars by 1.6 meters every hundred years. Phobos may hit the surface of Mars in the next 50 million years and form a ring around it after collapsing.

Phobos moon
A color-enhanced image of Phobos captured by HiRISE. This photo shows crater chains and grooves on this moon.

If one were to stand on the moon Phobos, one would see Mars occupying more of the sky. In the future, this may become a hobby. According to scientists, in the future, one of the moons of Mars may be used as a base to observe the Red Planet and send a robot to its surface.

Phobos and Deimos, like Earth’s moon, have a tidal lock; Which means that only one side of them can be seen from Mars. Both moons are irregular in shape, full of craters and impact craters covered in dust and small rocks. Phobos and Deimos are the darkest objects in the solar system. These moons are composed of carbonaceous rocks with ice, which may be the result of asteroid collisions.

The gravity of Phobos is one-thousandth of the Earth’s gravity. A person’s weight of 68 kg in Phobos reaches 68 grams. The names of the moons of Mars are derived from the mythological sons of Ares, the Greek counterpart of Mars, the Roman god. Phobos means fear or terror (phobia) and Deimos means escape (fleeing after defeat).

Deimos, the moon of Mars
Color-enhanced image of Deimos captured by HiRISE. This image shows the soft and smooth regolith cover of Deimos.

The wonders of the planet Mars

Humans have been seeing strange objects on the Martian surface for centuries. The reason for this issue can be the closeness of the conditions of Mars to host life or maybe Mars is close enough and can be observed more precisely. However, Earthlings were repeatedly fooled by the rocky surface of Mars and their illusions (such as finding channels to human faces and Martian bases); But all these findings turned out to be wrong. Here are some of the wonders of Mars:

Land and sea

According to Sir William Herschel’s notes in 1784, the dark areas of Mars are the oceans and the lighter areas are the Earth. According to the speculations of this famous British astronomer, Mars is surrounded by intelligent beings who probably have the same conditions as Earthlings. Herschel’s theory was the dominant theory for a century and even some astronomers claimed to have seen vegetation on the bright land of Mars. Fortunately, Herschel’s other astronomical achievements led to two powerful observatories being named in his honor. These theories were so strong that the Martian life theory was not very important.

land and sea

Giovanni Schiaparelli, an Italian astronomer, observed grooves on the surface of the Red Planet during his close observation of Mars in 1877. He used the Italian word canali, which means channel, to describe these grooves and concluded that Mars has intelligent life that made these waterways.

Another astronomer, Percival Lowell, 1895 presented a plan for Martian canals in his book entitled “Mars, the Abode of Life”, which increased the popularity of this misconception. The theory of Martian canals was rejected in the early 20th century. At that time, the channels proved to be just visual errors. When you see Mars with weak telescopes, the point-like features of mountains and impact craters appear continuous, forming smooth lines. By spectroscopic analysis of light received from Mars, it was later proven that there is no water on the surface of this planet.

Martian channels

In 1976, NASA released an interesting image of a Martian mountain captured by the Viking 1 probe. The image showed a face with eyes and a nose. The Martian face inspired numerous myths and conspiracy theories for about thirty years, and many people believed that an ancient Martian civilization had created the face.

From the aerial angle, the shadows of the mountains of Mars look like faces; But from other angles captured by the Mars Express orbiter and other probes, the Martian mountain does not look like a face. Pareidolia is a scientific and psychological term that refers to seeing familiar faces or objects in different places. Facial pareidolia is the result of increased sensitivity to the details of the human face.

face of mars

Arthur C. Clarke, the famous science fiction writer and author of “2001: A Space Odyssey”, announced seven years before his death that he saw streaks of vegetation, including trees, in new images from the Mars Global Surveyor. Clark says:

It’s like something like vegetation is moving with the seasons. I still hope we can find Martians. The branches and trees that Clark was talking about are actually geologically called “spiders”. These surface phenomena look like branches and change seasonally, But the reason for this is the seasonal melting of carbon dioxide ice covers in the poles of Mars. When the carbon dioxide ice is sublimated, it spreads in the form of branch streaks.

Martian tree

In 2007, the Spirit rover captured an interesting sight on the Red Planet: a person wearing what appears to be a robe and kneeling in prayer. The Spirit rover captured a panoramic image of Home Plate, which is located in the Gosef impact crater in the Columbia Range. Of course, the subject of this image is a stone that looks like a human due to the phenomenon of paridolia.

Gandhi’s face

The face of Mars in 1976 was only the beginning of such illusions. With the launch of Google Mars in 2009, users were able to see the surface of Mars and examine all kinds of roughness. This program was created from a set of compiled satellite images. An Italian man named Matteo Iannio, by examining these images, found a bump that resembled the appearance of Mahatma Gandhi, the Indian independence leader who was killed in 1948. Higher quality images showed that the said image is not related to a mountain or a hill; Rather, it is a pit that looks like a human in profile. The effect of pareidolia can be easily seen in the comparison of low-quality and high-quality images.

Gandhi's face on Mars

In 2011, another piece of evidence for the claim of life on Mars was unveiled. In a viral video on YouTube, someone claimed to have detected a human (extraterrestrial) base on Mars. He called this base “Alpha Biological Station”. Through Google Mars, he identified a linear and mysterious structure on the surface of the red planet.

Astronomers immediately identified a white structure that had become pixelated and of poor quality. This image was created due to the accumulation of cosmic rays in the image sensor of the camera that recorded this image. Alfred Ekayon, a planetary scientist at the Planetary and Lunar Laboratory of the University of Arizona and the head of the Planetary Image Processing Research Laboratory, says this: Such effects are common in space images taken by orbiting telescopes outside the magnetosphere.

Alpha biological station

The image received by the European Space Agency (ESA) orbiter in 2019 looks like a giant blue-haired spider with its feet on a Martian mountain. The reality is much more interesting. The legs of this spider are actually the paths of hundreds of small tornadoes or devil’s ovens. It is not yet clear why this mountain is the center of tornadoes; But according to ESA scientists, the movement of air masses in this area can lead to the formation of such tornadoes.

Blue spider

It seems that seeing creepy crawlies on Mars has become a hot topic. In 2019, William Romoser, professor emeritus, made an interesting claim. He claimed to have seen cockroaches and other insects and even reptiles on the surface of Mars. After examining the images received from NASA’s Mars rovers, Romoser observed raised shapes and vague ovals on the surface of Mars; But this time, Paridolia tricked him; Because the protruding shapes were mostly stones.

Martian beetle

Between July and September 2019, an object, possibly a meteorite or part of a comet, collided with the southern ice cap of Mars, puncturing a thin layer of the ice cap, and releasing red soil from the crater. The result of this incident was the emergence of a large red discharge that resembled cartoon characters hitting the wall. The large HiRISE (High Resolution Imaging Science Instrument) camera on the Mars Reconnaissance Orbiter (MRO) captured the leak, which is up to a kilometer across. This discharge was not a vision error and was completely fixed.

The Great Martian Discharge

As you know, Mars is a red planet; But what is this strange green stone (pictured below) doing on the red planet? The Perseverance probe captured the image of this rock. The length of this stone reaches approximately 15 cm and it is located in the impact crater of Yezro, which is close to the landing site of Perseverance. The Perseverance rover removed a portion of the rock to vaporize it. The rover’s cameras and spectrometers examined the resulting vapor cloud to reveal its chemical composition. The answer to this mystery will be revealed soon.

Strange green stone

Throughout history, Mars has only been observable at the closest distance to Earth. Martian perigee positions (closest to Earth) occur every 15 to 17 years. In the 17th century, Tycho Brahe measured the relative distance between Earth and Mars. The Cassini probe made more measurements. In 1610, Galileo was able to observe Mars with a telescope for the first time. Christian Huygens was also the first person to draw a map of the surface features of Mars. During the 20th century, with the beginning of the space age, observations and explorations increased at a remarkable rate.

So far, many probes have been sent to Mars, but almost one out of three missions were successful. In general, exploration programs pursue four main goals:

  • Investigating the existence of Martian life
  • Investigating the Martian climate
  • Survey of Martian geology
  • Preparing for human exploration

In the first Mars missions, which were simply flybys of the planet, spacecraft flew close to the surface of Mars and imaged it. NASA’s Mariner spacecraft was a small robotic probe developed to study the neighboring planets, including Venus, Mars, and Mercury. Mariner 4 passed by Mars in July 1965 and sent the first pictures of this alien world to Earth.

The thin atmosphere of Mars
The thin atmosphere of Mars makes it difficult for probes to land

In 1971, the Soviet Union managed to send its first spacecraft into Mars orbit and even sent a lander to touch its surface. The Mars 3 Orbiter also sent back data about the topography, climate, atmosphere, and geology of Mars for eight months. Although the lander of this probe managed to land on the surface of Mars, it lasted only 20 seconds.

Later, the Mariner 9 orbiter sent back more and more detailed images of the Martian atmosphere, mapping its surface, revealing the Martian topography, and capturing many images of this remote and strange world. The above missions solved some mysteries of Mars, including the legend of Martian canals and its ancient civilizations. On the other hand, they raised new questions about ancient Martian riverbeds that could indicate the presence of liquid water on this planet.

The Viking 1 and 2 spacecraft were a pair of orbiters and landers that reached Mars in 1976. These two probes continued to operate until the end of 1982 and surprised scientists by sending images of the surface of Mars. The Viking landers conducted biological experiments on the Martian soil and were supposed to find signs of life, but their results were not enough.

The thin atmosphere of Mars makes it difficult to land on the surface of this planet

The Mars Rover mission launched in 1996 paved the way for sending rovers. Sojourner, the rover of this spacecraft, sent information about the seasonal changes and weather of Mars, especially dust storms. The Mars Global Surveyor spacecraft has been in orbit since March 1999 with the aim of studying the surface of Mars.

The long-duration mission has provided new data on Mars’ changing seasons and weather, including dust storms. Mars Odyssey orbiter entered Mars orbit in 2001. The gamma-ray spectrometer of this spacecraft managed to discover significant amounts of hydrogen gas within a few meters of the surface of Mars.

The European Space Agency went to Mars in 2003 with the Mars Express probe. This probe was carrying a surface lander called Beagle 2, which disappeared in 2004. Beagle 2 was rediscovered in January 2015 by NASA’s Mars Reconnaissance Orbiter (MRO). During its mission, the Mars Express orbiter managed to discover methane in the Martian atmosphere, which is one of the necessary elements for the formation of life.

In January 2004, NASA landed its twin Mars rovers Sprite and Apchornity on the surface of Mars. Perhaps the most famous Mars missions are the Spirit and Opportunity rovers. These two rovers landed on both sides of Mars in January 2004 and began their extensive mission.

These two rovers examined several kilometers of the Martian soil and sent more than 100,000 high-quality images. They examined Martian rocks and soil and used laboratory modules equipped for geological tests on the Martian surface and subsurface. The mission of these two rovers was designed for 90 days, but they lasted for several years. The Spirit rover was active until 2010, and the Opportunity rover was shut down for good in 2018.

On March 10, 2006, the MRO (Mars Reconnaissance Orbiter) probe entered Mars orbit for two years of exploration. The orbiter began mapping the Martian surface and its climate with the aim of finding suitable landing sites for future missions. The MSL (Mars Science Laboratory) mission was launched on November 26, 2011 to send the Curiosity rover to the surface of Mars. This rover reached Mars on August 6, 2012. Curiosity is more advanced and larger than NASA’s previous rovers, and its maximum speed reaches 140 meters per hour. The rover’s experiments included laser chemical sampling and sending data on the composition of rocks.

Curiosity rover selfie
Selfie probe Curiosity

The MAVEN orbiter was launched on November 18, 2013, and landed at an altitude of 6,200 km on September 22, 2014, to study the Martian atmosphere. The goals of this mission include investigating the atmosphere and water of Mars in the distant past. The Indian Space Research Organization (ISRO) launched the MOM (Mars Orbiting Mission) spacecraft on November 5, 2013. This spacecraft was placed in Mars orbit on September 24, 2014. ISRO is the fourth space agency to reach Mars after the Soviet Union, NASA, and the European Space Agency.

The TGO orbiter reached Mars from Exomars in March 2016. Schiaparelli’s lander landed on Mars as an experiment. Schiaparelli hit the Martian surface but sent back key data about the parachute landing, so the test can be considered a partial success.

The second part of this mission is the Rosalind Franklin Rover. This rover was supposed to be launched in July 2020, but its launch was postponed until 2022. Following Russia’s invasion of Ukraine, the European Union, along with the United States, announced a list of new restrictive sanctions against Russia. According to the European Union, these sanctions cover the fields of finance, energy, transportation, technology, and passport issuance. Issa noted that he is complying with the sanctions. The organization wrote in its update:

We fully implement the sanctions imposed by our member states against Russia and evaluate the consequences of our current programs that are carried out in cooperation with the Russian Space Agency. In addition, we align our decisions in close coordination with industrial and international partners (especially with NASA and in the International Space Station program) and the decisions of the member countries of the organization.

Dmitry Rogozin, the head of Russia’s space agency, reacted quickly on Twitter, claiming that Isa was self-harming out of anger. If ExoMars is not launched in 2022, it will have to wait another two years until the next opportunity; Because it is only at that time that Mars and Earth are in the closest position to each other. In August 2012, NASA selected the $425 million InSight lander to explore the depths of the Martian surface. Two CubeSats named MarCO were launched together with InSight on May 5, 2018. The CubeSats separated 1.5 hours after launch and started their paths. The InSight probe successfully landed on the surface of Mars on November 26, 2018.

Perseverance mission

The Perseverance rover was launched from the Mars 2020 mission on July 30, 2020. This probe landed on the surface of Mars on February 18, 2021. Perseverance was also accompanied by a helicopter named Ingenuity. Twelve months later, Perseverance reached the mouth of Yezro, 45 km away. Based on the topography, it is clear that more than three billion years ago, Yezero was a body of water the same size as Lake Tahoe in America, and rivers flowed from the west and east of it. One of Perseverance’s first missions was to launch Ingenuity, a small robotic helicopter. Ingenuity is the first spacecraft to lift off from the surface of another planet. Perseverance also demonstrated the performance of oxygen generation technology, which is essential for manned missions to Mars.

In the next step, Perseverance investigated the bed of the Yazoro crater and it was found that the rocks of this crater are far from the expectations of scientists. Perseverance had trouble collecting stone cores several times. The rover will mine rock material in cylinders about the size of chalkboard chalk that will be returned to Earth on future missions. Ingenuity was one of the last additional parts of the mission, which was intended to prove the feasibility of flying in the thin air of Mars. On April 18, 2021, Igneoti soared to a height of three meters, flew for 30 seconds, and then returned to the ground. This flight lasted a total of 39.1 seconds.

Ingenuity helicopter
The Ingenuity helicopter is preparing for its first flight.

Ingenuity’s mission was supposed to end after four flights; because Perseverance should have abandoned it and continued scientific research; But NASA decided that five flights were not enough. As Perseverance began exploring the rocks to the south, Ingenuity’s helicopter accompanied it and surveyed the terrain ahead of the rover. Thus, the rover’s time is not wasted by hitting unexpected rocks.

Perseverance surprised scientists by examining and excavating rock samples south of its landing site. Perseverance’s instruments to examine the materials that makeup Martian rocks examine their tiny grains, which are as small as a grain of sand. The cameras on the robotic arm can also record close-up images. In the observations, large olivine particles were seen; An igneous rock mineral that can accumulate in the bed of a large lava flow. Other pieces appeared between the olivine particles that were filled with carbonate; A mineral that is formed by reacting with water.

Perseverance is the first step of mankind in realizing the dream of bringing Mars samples to Earth. This probe creates holes in the rocks and holds them in insulated pipes. Since Perseverance has no way to send rock samples back to Earth, another spacecraft will have to send them home later. This mission is called “Mars Sample Return” and is a joint project of NASA and the European Space Agency.

The first selfie of the InSight rover showing its solar panels
Valais Marineris Valley or the Grand Canyon of Mars from the perspective of Viking One
Sand dunes on the northern plateaus of Mars
A crater full of ice
Mars from the Hubble Space Telescope
Yezro Crater, the place of Mars rover Perseverance's discoveries
Curiosity rover selfie
Dry ice or carbon monoxide ice on Mars
Image gallery of Mars exploration missions

Human exploration of Mars has had many supporters since the early days of the space age. Robert H. Goddard used the idea of ​​a trip to Mars as an incentive to study physics and aerospace engineering. Various proposals for human exploration of Mars have been presented throughout the history of the space age. Currently, active plans and programs to send humans to Mars in the next ten to thirty years have been presented at the government and private levels.


In 2004, the then President of the United States, George W. Bush, announced the program of human exploration of Mars. Urine spacecraft will be used to send space crews to the moon by mid-2020. In the next phase, the moon will become a way station for the journey to Mars. On September 28, 2007, then NASA administrator Michael D. Griffin announced that he would send humans to Mars by 2037. On October 8, 2015, NASA released the official plan for Mars exploration and colonization. They named this project “Journey to Mars”. This plan has three stages to sustainable colonization.

  • The first phase that is being implemented is called the “ground-dependent” phase. At this stage, until 2024, the International Space Station will be used to evaluate technologies and investigate the effects of long-duration space missions on the human body.
  • In the second stage, titled “Proof Field”, the dependence on the Earth will be removed and for most of the tasks, the space of Cis Luna (Moon orbit to the surface of the Moon) will be used.
  • The final phase, the “Earth-independent phase,” involves long-duration missions to the lunar surface. At this stage, the resources of Mars are used for fuel, water, and building materials. NASA’s goal is to send humans to Mars by the mid-2030s, although independence from Earth may be a little later.


The long-term goal of the private company SpaceX is to plan space flights to Mars and colonize the planet. To achieve this goal, this company is developing a spacecraft called Starship, which is capable of transporting crew to Mars and other solar system objects. In 2017, SpaceX announced plans to send two unmanned starships to Mars by 2022, followed by two more unmanned and manned starships in 2024. Starship is supposed to carry at least 100 tons of cargo.

Starship SN15 and SN16

Mars is a harsh environment for human life. In the long term, various technologies have been developed to aid long-term space exploration, and these technologies may be used for Mars as well. The longest duration of human stay in space is 438 days recorded by Valery Pliakov. The longest time spent outside Earth’s Van Allen Belt is about 12 days, dating back to the Apollo 17 moon landing. This period is very short compared to NASA’s 1,100-day journey in the next decade. On the other hand, according to scientists, traveling to Mars will have harmful biological effects on the human body. Due to the high radiation, the physical effects of living on Mars are increased.

Many missions to Mars are being developed and planned that will pave the way for human travel. Scientists hope the robotic probes will send back data about underground activity as well as the geology of Mars and take samples. Such missions could discover more signs of life and water on the planet. Maybe life is hidden under the layers of the Martian surface.


Pluto; Everything you need to know




Pluto is a dwarf planet and the largest mass in the Kuiper belt, which was once known as the ninth planet in the solar system; But later he lost this position.

Pluto; Everything you need to know

Pluto or Pluto is the largest known dwarf planet in the solar system, which used to be the ninth and outermost planet in the solar system. This strange world is located in the Kuiper Belt; A region beyond Neptune’s orbit with hundreds of thousands of rocky and icy bodies each more than 100 kilometers across, as well as a trillion or more comets.

Pluto was reclassified as a dwarf planet in 2006 and lost the title of ninth planet. The demotion of Pluto was a controversial event and provoked serious discussions in the scientific community and among people.

Table of Contents
  • How was Pluto discovered?
  • What does Pluto look like?
  • What is Pluto made of?
  • Orbital features of Pluto
  • Interesting facts about Pluto’s orbit
  • Why is Pluto no longer a planet?
  • Does Pluto have moons?
  • Journey to Pluto
  • Pictures of Pluto and its moons

How was Pluto discovered?

Percival Lowell, an American astronomer, first proposed the existence of Pluto in 1905 when he observed strange deviations in the orbits of Uranus and Neptune. Lowell thought there must be another object whose gravity was affecting the ice giants, causing them to misalign their orbits. Lowell predicted the position of the mysterious planet in 1915, But he died 15 years before its discovery. Finally, based on the predictions of Lowell and other astronomers, Clyde Tamba discovered Pluto in 1930 at the Lowell Observatory in Arizona.

Clyde Tamba discovered the dwarf planet Pluto
Clyde Tamba, discoverer of the dwarf planet Pluto.

Pluto was named by the suggestion of Venisha Burney , an 11-year-old child from England. With the news of the discovery of the ninth planet, Venisha suggested to her grandfather that the name of the god of the underworld in Roman mythology be placed on it. His grandfather then passed the suggested name on to the Lowell Observatory. Pluto is also considered to be a tribute to Percival Lowell because it contains the first two letters of Percival Lowell’s name.

What does Pluto look like?

Because Pluto is so far from Earth, little was known about the dwarf planet’s size or surface condition until 2015, when NASA’s New Horizons spacecraft flew past it. New Horizons showed that Pluto, with a diameter of 2,370 kilometers, is less than one-fifth the size of Earth and only about two-thirds the size of our planet’s moons.

New Horizons’ observations of Pluto’s surface revealed various surface features; Among the mountains whose height reaches 3500 meters and are comparable to the Rocky Mountains on Earth. Although frozen methane and nitrogen cover most of Pluto’s surface, these materials are not strong enough to support such high peaks; As a result, scientists believe that the mountains were formed on a bed of water ice.

The surface of Pluto as seen by the New Horizons spacecraftThe surface of Pluto was seen by NASA’s New Horizons spacecraft in July 2015.

Pluto’s surface is covered with an abundance of frozen methane, But New Horizons scientists have observed dramatic differences in the way light reflects off this icy surface across the surface of the dwarf planet. They have observed features similar to Earth’s ice sheets or erosion features in Pluto’s mountainous regions. These surface effects are much larger on Pluto; As it is estimated that their height is 500 meters; While the size of ground samples is only a few meters.

Another distinctive feature on Pluto’s surface is a large heart-shaped region known informally as the Tamba region. The left side of this area (the area that takes the shape of an ice cream cone) is covered with frozen carbon monoxide. Scientists have detected other changes in the composition of surface materials in the “heart” of Pluto.

At left center of the Tamba region is a very flat area that the New Horizons team has informally named the “Sputnik Plateau” in honor of Sputnik, the first artificial satellite to orbit Earth. This region of Pluto’s surface does not have craters caused by meteorite impact; A feature that shows that the Sputnik Plateau is geologically a very young region that is not more than a hundred million years old. It is possible that this area is still being formed and changed by geological processes.

Pluto’s ice plains show dark streaks several kilometers long that lineup. It is possible that these lines were formed by strong winds that blow on the surface of the dwarf planet. The Hubble Space Telescope has also obtained evidence that Pluto’s crust could contain complex organic molecules.

Pluto’s surface is one of the coldest places in the solar system. The temperature there can drop to minus 226 to minus 240 degrees Celsius. Comparing images taken of Pluto at different times showed that the dwarf planet appears to have become redder over time, possibly due to seasonal changes.

Pluto may have a subsurface ocean now or may have had one in the past. However, there is still no consensus on this. If an ocean had already formed under the surface of Pluto, it could have greatly influenced the history of this dwarf planet. For example, scientists believe that the Sputnik Plateau region grew so heavy over time as the ice mass increased that it overturned Pluto and brought its axial tilt to its present size (about 120 degrees). According to researchers, the subsurface ocean is the best explanation for this phenomenon. If Pluto has a liquid ocean and enough energy, it could be a haven for life.

What is Pluto made of?

Some of the elements that make up Pluto, according to NASA, are as follows:

Composition of the atmosphere: methane and nitrogen. New Horizons observations show that Pluto’s atmosphere extends up to 1,600 km above the surface of this dwarf planet.

Magnetic Field: Scientists still don’t know if Pluto has a magnetic field or not, But the dwarf planet’s small size and slow rotation suggest that such a field is weak or non-existent.

Chemical composition: Pluto is probably composed of a mixture of 70% rock and 30% water ice.

Internal structure: The dwarf planet probably has a rocky core surrounded by a mantle of water ice, and unusual frozen elements such as methane, carbon monoxide, and nitrogen cover its surface.

Orbital features of Pluto

Pluto’s highly elliptical orbit can take it over 49 times the distance from Earth to the Sun. Because the dwarf planet’s orbit is highly eccentric, or non-circular, Pluto’s distance from the Sun can vary dramatically. The dwarf planet was actually closer to the Sun than Neptune for 20 years of its 248-year orbital period, giving astronomers a rare opportunity to study this small, cold, and distant world.

As a result of such an orbit, after being considered the eighth planet from the Sun for 20 years, Pluto passed the orbit of Neptune in 1999 and became the farthest planet from the Sun until it was finally demoted to a dwarf planet in 2006.

As Pluto moves closer to the Sun, its surface ice melts, temporarily forming a thin atmosphere composed mostly of nitrogen and some methane. The insignificant gravity of Pluto, which is a little more than one-twentieth of the gravity of the Earth, causes this atmosphere to expand to a much higher height compared to the Earth’s atmosphere.

As the dwarf planet moves farther from the Sun, much of its atmosphere appears to freeze and disappear. However, when Pluto has an atmosphere, it can probably experience strong winds. This atmosphere also has changes in brightness, which can be caused by gravity waves or airflow over the mountains.

Although Pluto’s atmosphere is too thin to allow liquids to flow today, liquid elements may have flowed on the dwarf planet’s ancient surface in the past. New Horizons captured an image of a frozen lake in the Tampa area that appeared to have ancient waterways nearby. At one point in its history, Pluto could have had an atmosphere almost 40 times thicker than that of Mars.

Artist rendering of NASA's New Horizons probeArtist’s rendering of NASA’s New Horizons spacecraft.

In 2016, scientists announced that they may have observed clouds in Pluto’s atmosphere using data from New Horizons. The researchers saw seven bright objects that were located near the boundary between light and dark. This area is usually where clouds form. These possible clouds were all at low altitudes and almost the same size, which indicates that they are separate complications. The composition of the clouds, if they really exist, would probably be acetylene, ethane, and hydrogen cyanide.

Interesting facts about Pluto’s orbit

  • Pluto’s rotation is retrograde compared to other worlds in the solar system; This means that the dwarf planet rotates backwards and from east to west.
  • The average distance from the sun: 5,906,380,000 km or 39.4 astronomical units.
  • Periphery (shortest distance to the Sun): 4,434,987,000 km or 30.1 AU.
  • Apogee (farthest distance from the Sun): 7,304,326,000 km or 48 AU.
  • Pluto’s orbital path around the Sun is not in the same plane as the eight planets of the solar system; Rather, it is located at an angle of 17 degrees.
Pluto's orbit around the Sun compared to the planets of the Solar SystemPluto’s orbit around the Sun compared to other planets and the asteroid belt.

Why is Pluto no longer a planet?

Those who went to school until 17 years ago and before that, had learned in textbooks that Pluto is the ninth planet of the solar system. But in August 2006, the International Astronomical Union (IAU) downgraded Pluto to a “dwarf planet”. This meant that from then on, only the rocky worlds of the inner solar system and the gas giants of the outer reaches of the planet were considered.

The “inner solar system” is a region of space smaller than the radius of Jupiter’s orbit around the Sun. This range includes the asteroid belt as well as rocky planets such as Mercury, Venus, Earth, and Mars. Gas giants including Jupiter, Saturn, Neptune, and Uranus also form the outer limits of the solar system. As a result, now we have eight planets instead of nine.

According to the IAU definition, a “dwarf planet” is a celestial body that orbits directly around the Sun and has enough mass to be controlled by gravitational forces rather than mechanical forces, and as a result, is elliptical in shape; But it doesn’t clear the surrounding area from other objects. The three IAU criteria for a planet are as follows:

  • It revolves around the sun.
  • It has cleared the area around its orbit.

Pluto only meets the above two conditions and does not meet the third criterion, and in all the billions of years it has existed at this point, it has not been able to clear its vicinity. You may ask, what does “clearing the surrounding area of ​​other objects” mean? This condition means that the planet is dominated by gravity and there is no other body of similar size in its vicinity, except for moons or objects that are influenced by its gravity; While Pluto shares its neighborhood with Kuiper belt objects like plutinos.

Some scientists in recent years have demanded that by changing the definition of a planet, Pluto will return to the group of planets in the solar system. However, if this happens, the number of planets in our cosmic neighborhood may exceed the current number.

Does Pluto have moons?

Pluto has five moons: Charon, Stokes, Nyx, Cerberus, and Hydra, of which Charon is the closest moon to Pluto and Hydra is the farthest.

In 1978, astronomers discovered that Pluto has a very large moon, almost half the size of the dwarf planet itself. This moon was named Charon or Kharon, inspired by the spirit-carrying creature in Greek mythology that led souls to the underworld.

Because Charon and Pluto are so similar in size, their orbits differ from those of most of the planets and their moons. Much like binary star systems, Pluto and Charon both orbit a point in space that lies between them. For this reason, scientists refer to Pluto and Charon as a binary dwarf planet, binary planet, or binary system.

Pluto and its moon CharonComposite of color-enhanced images of Charon (top left) and Pluto (bottom right) taken by the New Horizons spacecraft in 2015.

Pluto and Charon are only 19,640 kilometers apart, or less than the distance between London and Sydney by plane. Charon’s orbit around Pluto takes 6.4 Earth days, and one Pluto revolution (one Pluto day) takes the same amount of time. The reason for this is that Charon hovers over the same point on Pluto’s surface, and the same side of the moon is always seen from the dwarf planet. This phenomenon is called fatal lock.

While Pluto has a reddish hue, Charon appears more grayish. This moon may have contained a subsurface ocean in the early days of its formation; But today, it probably cannot support such a complication. Compared to most of the planets and moons of the solar system, the system of Pluto and Charon is turned sideways with respect to the Sun.

New Horizons observations of Charon revealed the existence of valleys on the moon’s surface. The largest Sharon valley is 9.7 km deep, and a large mass of rocks and depressions stretches 970 km in the middle of the moon. A part of the moon’s surface near one pole is covered with much darker material than the rest.

Much of Charon’s surface is similar to Pluto’s crater-free regions, indicating that the moon is quite young and geologically active. Scientists have observed evidence of landslides on Charon’s surface, the first observation of such phenomena in the Kuiper Belt. The moon may also have its own form of plate tectonics; A phenomenon that causes geological changes on earth.

In 2005, in preparation for NASA’s New Horizons mission, scientists photographed Pluto using the Hubble Space Telescope and found two other small moons of this dwarf planet. These moons, named Nyx and Hydra, are two and three times more distant from the dwarf planet than the distance between Charon and Pluto. Based on New Horizons measurements, the length and width of Nix are estimated to be 42 and 36 kilometers, respectively; While Hydra is 50 km long and 30 km wide. It is likely that the surface of Hydra is mainly covered by water ice.

Pluto and its moons from the Hubble Space TelescopePluto and its moons from the Hubble Space Telescope.

Using the Hubble telescope, scientists discovered Pluto’s fourth moon, Herbrus, in 2011. This moon has a two-part shape, the big part is about 8 km long and the small part is about 5 km wide. On July 11, 2012, a fifth moon named Stokes (with an estimated diameter of 10 km) was discovered, further fueling the debate over Pluto’s planet status.

The main hypothesis for the formation of Pluto and Charon is that the nascent Pluto had a surface collision with another body of its size. According to this idea, most of the combined material of the two bodies became Pluto and the other remnants formed Charon. The other four moons may have formed from the same collision that created Charon.

Journey to Pluto

The New Horizons spacecraft is the first probe to closely study Pluto, its moons, and other Kuiper Belt worlds. The spacecraft was launched in January 2006 and successfully made its closest approach to the dwarf planet on July 14, 2015. The New Horizons probe is carrying some of the ashes of Pluto discoverer Clyde Tamba.

Limited knowledge of the Pluto system created unprecedented risks for the New Horizons probe. Before the mission launch, scientists knew of only three moons around Pluto. Herbrus and Stokes’ discovery during the spacecraft’s journey fueled the idea that more unseen moons may be orbiting the dwarf planet. Hitting these hidden moons or even small debris could seriously damage the spacecraft. However, the New Horizons team equipped the space probe with tools to protect it during its journey.

In October 2015, New Horizons made history by sending the first close-up images of Pluto and its moons. You can see these amazing pictures at the end of the article.

Currently, no other mission after New Horizons is officially planned to visit Pluto; But at least two conceptual designs are under study. In April 2017, a workshop was held in Houston, Texas to discuss ideas for the next Pluto mission. Possible goals discussed by the team for such a mission include mapping the surface with an accuracy of 9 meters per pixel, observations of Pluto’s smaller moons, how Pluto changes as it rotates on its axis, and topographic mapping of regions darkened by the dwarf planet’s axial tilt. They are long-term.

New Horizons principal investigator Ellen Stern believes that if an orbiter were sent to study Pluto, we could map 100 percent of the dwarf planet, even the surfaces in total shadow. New Horizons data indicated the possible existence of a subsurface ocean on Pluto, and researchers believe that the orbiter mission can also find evidence of such a complex.

Pictures of Pluto and its moons

Blue haze surrounding the dwarf planet PlutoAfter passing by Pluto, New Horizons looked back to photograph the blue dust surrounding the dwarf planet.
Charon is the largest moon of PlutoEnhanced color image of Charon, Pluto’s largest moon.
Snakeskin texture on part of Pluto's surfaceEnhanced color image of the “snakeskin” texture on part of Pluto’s surface.
The edge of the Sputnik Plateau on PlutoColor-enhanced image of the edge of the Sputnik Plateau, the icy plain that forms the left side of Pluto’s heart-shaped region.
Pluto's atmospheric dust over its rugged mountains and icy plainsPluto’s atmospheric dust over the rugged mountains and icy plains of this dwarf planet.
A partial view of the sunset on PlutoA partial sunset view shows rugged mountains with a maximum height of 3,350 meters.
Pluto's Sputnik PlateauSputnik plateau. The images used to make this composite photo were taken from a distance of 80,000 km.
Nix, Pluto's moon, from the perspective of New HorizonsLow-resolution image of Nix, a moon of Pluto.
Pluto's moon Hydra as seen by New HorizonsLow-resolution image of Hydra, Pluto’s moon.

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Why was Pluto removed from the list of planets in the solar system?




More than 17 years have passed since the demotion of Pluto from a planet to a dwarf planet, But experts and the public still debate Pluto’s status and planet definition.

Why was Pluto removed from the list of planets in the solar system?

Our understanding of the solar system changed forever on August 24, 2006. At that time, the International Astronomical Union (IAU) researchers agreed to reclassify Pluto, changing the status of this object from a planet to a dwarf planet. This decision provoked a lot of anger and caused the textbooks to be rewritten. The demotion of the former ninth planet of the solar system is still controversial after more than 17 years.

Currently, the discussion about Pluto shows the problems in defining the concept of “planet”. The International Astronomical Union defines a planet as a celestial body that orbits the Sun with a nearly spherical appearance and, in most cases, clears the vicinity of its orbit of debris from other bodies. However, this set of criteria has not been universally agreed upon.

Earth and even Jupiter, despite their large size, have not cleared many asteroids from their orbital regions. In addition, there are small worlds such as Ceres that are spherical and revolve around the Sun, and are not considered planets.

Table of Contents
  • After all, what is a planet?
  • A planetary puzzle
  • NASA’s New Horizons mission and the debate over the planet again
  • Can Pluto become a planet again?
  • What is the significance of Pluto being a planet?

Pluto’s demotion raises larger issues about how to define everybody in the solar system, or even space more generally. This incident shows that science sometimes cannot divide objects into easy categories; Because if the definition of planet is expanded again, it is not clear how we should evaluate the numerous non-spherical bodies that orbit the Sun. Decisions about this may even call into question the asteroid belt (the huge band of small objects between Mars and Jupiter). Or what happens if a planet somehow breaks into pieces?

The discussion about Pluto shows the problems in defining the concept of “planet”.

Meanwhile, while the Pluto debate began almost 20 years ago, many still don’t fully understand all the controversy and why Pluto lost its planetary status. But the change in the number of planets in the solar system from nine to eight (at least according to the standard IAU definition) was long in the making and highlighted one of science’s greatest strengths: the ability to change seemingly fixed definitions in light of new evidence.

After all, what is a planet?

The word planet in English (Planet) goes back to ancient times and is derived from the Greek word Planetes meaning “wandering star”. The five classical planets—Mercury, Venus, Mars, Jupiter, and Saturn—are visible to the naked eye and move in strange paths across the sky compared to the much more distant background stars.

After the advent of telescopes, astronomers discovered two new planets, Uranus and Neptune. These two distant worlds are very dim and cannot be seen with the naked eye. It should be kept in mind that the discussed definition of a planet follows the Greek-Roman tradition and the definitions of the International Astronomical Union are based on it. In ancient times, the planets were observed with the naked eye all over the world and had different names in each culture.

When astronomers discovered Ceres in the asteroid belt in 1801, it was classified as a “planet” by the scientific community at the time. But the situation began to change; Because further measurements showed that Ceres is smaller than any other planet seen so far. This mass then entered a group of rocky bodies called “asteroids”, of which we now know hundreds of thousands of examples in the asteroid belt alone. Today, Ceres is known as a dwarf planet.

Comparing the size of Earth and Moon with Pluto and CharonSize comparison of Pluto and its moon Charon (bottom right) with the Moon and Earth.

Pluto was discovered and classified as a planet in 1930 (11 years after the founding of the International Astronomical Union). At the time, Clyde Tamba of the Lowell Observatory in Arizona compared photographic plates of the sky on separate nights and noticed a small dot moving back and forth across the starscape. However, the latest candidate for the ninth planet of the solar system was immediately considered a strange object. Pluto’s orbit is so elliptical, or eccentric, that it brings the object closer to the Sun than Neptune in 20 years of its 248-year journey. Pluto’s orbit is also tilted relative to the ecliptic, or the plane on which the other planets in the solar system rotate.

If Pluto is a planet, then is Eris also a planet?

In 1992, scientists discovered the first Kuiper Belt object named 1992 QB1. This small body orbits the Sun in the vicinity of Pluto and beyond the orbit of Neptune. Soon many similar objects were discovered, and a belt of small, icy worlds similar to the asteroid belt between Mars and Jupiter was revealed. Pluto remained king of this region until, in July 2005, astronomers discovered the distant object Eris, which was initially thought to be larger than Pluto.

A planetary puzzle

After the discovery of Eris, researchers had to ask themselves these questions: If Pluto is a planet, then is Eris also considered a planet? What about all those other icy bodies in the Kuiper Belt or smaller bodies in the Asteroid Belt? Where exactly is the dividing line for classifying an object as a planet? A word that once seemed straightforward and simple suddenly became strangely complicated.

Then intense debates ensued and new proposals were made to define the planet. Brian Marsden, a member of the IAU executive committee responsible for finding a new meaning for the planet, told in 2005: “Every time we think some of us are reaching a consensus, then someone says something and shows that it’s clear.” It’s not like that.”

A year later, astronomers were still nowhere near a solution, and the dilemma hung over the IAU General Assembly in Prague in 2006 like a dark cloud. At this conference, the researchers had eight days of intensive discussion and presented four different proposals. A controversial proposal would have brought the total number of planets in the solar system to 12 by adding Ceres, the largest asteroid, and Pluto’s moon, Charon.

Michael Brown, an astronomer at Caltech University and discoverer of Eris, called the proposal “complete confusion.”

Planets and dwarf planets of the solar systemThe globular objects in the Kuiper Belt (right arrows) and Ceres (left arrow) are now called dwarf planets.

Near the end of the conference, the remaining 424 astronomers voted to create three new classifications for objects in the solar system. From then on, only Mercury and Neptune and the large worlds in between were considered planets. Then Pluto and its counterparts (round bodies that shared their orbits with other bodies) were called dwarf planets. All other objects that orbit the Sun are known as minor solar system bodies.

NASA’s New Horizons mission and the debate over the planet again

A group of experts did not take the decision of their colleagues seriously. Alan Stern, the senior researcher of NASA’s New Horizons spacecraft, which passed by Pluto in 2015, regretted the demotion of the former ninth planet of the solar system and said that less than five percent of the world’s 10,000 astronomers participated in the International Astronomical Union vote.

New Horizons was considered an important turning point in the planetary debate. The spacecraft’s quick flyby of Pluto revealed a world far more dynamic than anyone imagined. Large mountains, impact craters, and signs of liquid nitrogen flowing on the surface all suggest a world that has undergone significant geological changes since its formation. People like Stern have argued that Pluto should be considered a planet on that basis alone.

New Horizons was considered an important turning point in the planetary debate

Images taken from Pluto’s moon Charon also show a very dynamic place; Including the red cap on its pole, which apparently changes its appearance with the slow seasonal change in the solar system. Most importantly, Pluto has several moons; While Mercury and Venus, the two inner planets of the solar system, do not have even one moon. Many asteroids and dwarf planets also have moons, complicating the definition of a planet.

An artist's rendering of the New Horizons spacecraft over PlutoNew Horizons is the only spacecraft that has ever had a close encounter with Pluto.

Many people share views with Stern and other like-minded experts. In 2014, shortly before New Horizons flew past Pluto, experts at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, debated different definitions of the planet. Owen Gingerich, a science historian who chairs the IAU’s Planet Definition Committee, stated that “planet is a culturally defined term that changes over time.” But most of the audience watching the CfA debate chose a different definition that would have put Pluto back among the planets.

Alternative classification schemes continue to be proposed. A 2017 proposal defined a planet as “a spherical body in space that is smaller than a star.” This definition makes Pluto a planet again; But it does the same with Earth’s moon, as well as many other moons in the solar system, bringing the total number of officially recognized planets to 110. A year later, Stern wrote an op-ed in The Washington Post with David Greenspoon, senior scientist at the Planetary Science Association, arguing that the International Astronomical Union’s definition was hastily adopted and problematic and that astronomers should rethink their ideas.

Can Pluto become a planet again?

Numerous requests from experts have so far been ignored, and the International Astronomical Union is unlikely to address the dispute anytime soon. “The simple fact is that Pluto was misclassified at the time of discovery,” wrote American astrophysicist Ethan Siegel in response to Stern and Greenspoon. “This crime has never been in the same position as the other eight worlds.”

Michael Brown also says: “As a result, Pluto is still not a planet, and in fact it never was.” We just got it wrong for 50 years and now we know better. Missing Pluto is not really a very good argument. “The reality is something else and we have to deal with it.”

What is the significance of Pluto being a planet?

The Sun and the planets of the solar system opposite Pluto

These days, children who weren’t even born when Pluto was a planet, ask what the definition of a planet even matters. Why do we have to discuss whether Pluto is a planet or not? Astronomers say there’s no simple answer, and we may have to look beyond our own solar system to understand what makes an object a planet or not.

More than five thousand exoplanets or worlds beyond the solar system have been discovered so far. This vast collection ranges from Earth-sized “super-Earths” to Uranus and “hot Jupiters” orbiting their star closely, to a range of worlds of other sizes. The types of planetary environments that must be considered are changing rapidly.

It seems unlikely that the International Astronomical Union will address the Pluto controversy anytime soon

What the increasing knowledge of the types of exoplanets shows us is that each star system may have its own unique environment. Although it can be more generally stated that stars can form planets from the collapse of gas and dust in their environment, the unique dynamics that control the process of planet formation are much more complex. For example, are multiple stars involved in this process? How much dust is there? Is there a black hole or supernova that will destroy the precious dust and gas needed to grow planets?

Even if planets are lucky enough to grow large, how they interact with other planets early in their formation is poorly understood. The worlds interact with each other, and the mutual gravitational effect between them causes the planets to move away from their parent star, close to it, or in some cases, fall out of the system altogether.

What all these explanations suggest is that our definition of a planet should probably be more contextual to account for the number of possible scenarios for the formation of worlds. Perhaps the planets depend on a specific formation condition or specific regions. All we seem to know for sure is that as more and more data is collected, the planet definition and the debate that Pluto has sparked will continue for some time to come.

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The planet Jupiter; Everything you need to know




Jupiter is the largest planet in the solar system and is highly regarded for its fascinating features such as the Great Red Spot and mysterious icy moons such as Europa and Ganymede.

The planet Jupiter; Features, moons, wonders, and everything you need to know

The planet Jupiter, known by other names such as Hormuz, Hormuz, or Jupiter, is the fifth and largest planet in the solar system. Jupiter has played a major role in the evolution of the history of the solar system and it can be said that the earth owes its survival to Jupiter.

This planet is one of the gas giants along with Saturn. The other two planets Uranus and Neptune are in the category of ice giants of the solar system. Jupiter is a mixture of hydrogen and helium, and due to its high rotation speed, its shape is not perfectly spherical. Jupiter’s outer atmosphere is divided into several bands with different latitudes, at the meeting points of these atmospheric bands, storms and eddy currents arise. One of the common points of these strips is the famous big red spot; A huge storm that was first observed with a telescope in the 17th century.

Jupiter has a faint ring and a strong magnetosphere. This planet, also called the king of planets, has 79 confirmed moons. In terms of the number of moons, Jupiter ranks second in the solar system after Saturn (with 82 moons). The most famous moons of this planet are a set of four known as the Galilean moons, which were discovered in 1610 by the Italian scientist Galileo Galilei. Ganymede is the largest moon of Jupiter and the largest moon in the entire solar system.

Robotic spacecraft have done a lot of research on Jupiter. Among the most famous Jupiter missions, we can mention the Voyager and Pioneer missions and then the Galileo orbiter. In late February 2007, the New Horizons probe visited Jupiter and used the planet’s gravity to increase its speed and get in the path of Pluto. The last mission to Jupiter was carried out by the Juno probe, which entered the orbit of the planet on July 4, 2016.

Table of Contents
  • Ten interesting facts about the planet Jupiter
  • What does the planet Jupiter symbolize?
  • How was Jupiter formed?
  • Disk instability model
  • Gravel accumulation
  • Customer relocation
  • Jupiter is how much bigger than Earth?
  • Physical characteristics and internal composition of the planet Jupiter
  • Jupiter’s atmosphere and cloud layers
  • Jupiter’s Great Red Spot
  • Jupiter’s magnetic field
  • Rotation and orbit of Jupiter
  • How many moons does Jupiter have?
  • group of moons
  • Irregular moons of Jupiter
  • Galilean moons
  • Moon Io
  • Callisto’s moon
  • Ganymede’s moon
  • Europa’s moon
  • Customer rings
  • Wonders of Jupiter
  • Seeing Jupiter from Earth
  • Pre-telescopic researches
  • Ground-based telescopic research
  • Radiotelescopic researches
  • Jupiter probes
  • Pioneer 10 and 11 (Pioneer)
  • Voyager 1 and 2
  • Galileo Spacecraft
  • Cassini spacecraft
  • Ulysses spacecraft
  • New Horizons spacecraft
  • Juno spacecraft
  • Images by James Webb of Jupiter
  • Future missions to the client
  • common questions

Ten interesting facts about the planet Jupiter

1. Jupiter is the largest planet in the solar system, which is named after the god of the sky and thunder. This planet is mainly composed of gas (hydrogen and helium) and its inner core is almost the same size as Earth.

2. The planet Jupiter has at least 79 moons, of which the four big red ones are: Io, Europa, Ganymede and Callisto (these moons are also known as Galilean moons in honor of Galileo). Although Jupiter cannot host life, some of its moons have the potential for life due to the existence of subsurface oceans.

3. Jupiter rotates around itself faster than any other planet, and this causes streaks: dark areas (belts) represent rising clouds and gases; Bright areas (areas) indicate belt subsidence.

4. Jupiter’s rotation speed is fast at the equator and slow at the poles; Thus, the gas layers in the impact areas cause white spots, spiral storms, and vortices. One of Jupiter’s most famous storms is the Great Red Spot, three times the size of Earth. This is not a permanent storm.

5. Jupiter has four rings. The Voyager 1 probe discovered these rings in 1979. These rings are very faint and were made of dust particles, unlike Saturn’s transparent rings, which are composed of ice and rock.

(from top to bottom): Jupiter’s Great Red Spot, Io, Europa, Ganymede, Callisto

During its mission, the Juno probe has also reached interesting facts about the planet Jupiter, which we mention:

6. Jupiter’s atmosphere is amazing. According to Juno’s findings, this gas giant is much more turbulent than expected. Cloudy and windy weather is not seen only in the upper layer of this planet. Rather, these winds exist thousands of kilometers deep in Jupiter. Also, surprisingly, Jupiter’s bands disappear near its poles.

7. According to the hypotheses, Jupiter’s famous gas clouds (a mixture of water and ammonia) are equally mixed. However, there is less ammonia on the surface and more ammonia is concentrated in the core.

8. At Jupiter’s north and south poles, circular chains of massive tornadoes are flowing. These rotating storms are very dense in the dimensions of the continents of the earth. Their length reaches 48 kilometers and their width reaches hundreds of kilometers.

9. Jupiter’s solid core is not fully compressed at its center. Rather, it is an inflated sphere in the dimensions of half the diameter of Jupiter. No one knows what is the reason for this problem, but according to the hypotheses, a heavy mass collided with Jupiter, which caused its core to combine with other surrounding gases.

10. Jupiter has the strongest magnetic field in the Solar System, but Juno shows it’s even stronger than expected, closer to the planet’s surface. Also, Jupiter’s north and south poles are not the same.

What does the planet Jupiter symbolize?

The planet Jupiter has been known since ancient times. This planet is also known by many names in different cultures such as Jupiter (Roman culture), Burgess, Urmazd, and Zavash. Jupiter can be seen in the night sky with the naked eye and sometimes during the day (when the sunlight is low). The Romans named this planet after one of the gods of Roman mythology, Jupiter (also known as the god of love).

The Babylonians knew Jupiter by the name of their god, Marduk. They used Jupiter’s 12-year period next to the ecliptic to define the zodiac constellations. The Romans considered Jupiter a star. On the other hand, in Greece, Jupiter was known as Zeus (the equivalent of the Roman god Jupiter). The ancient Greeks knew this planet as Phaeton, which means shining or burning star. The origin of the astrological symbol of Jupiter (image below) is not known, But many consider it to be a symbol of lightning, and according to new reports, this symbol is based on the Egyptian hieroglyphic script that means eagle.

It has been nearly 13.8 billion years since the Big Bang and the beginning of the universe, and almost 4.6 billion years since the formation of the solar system. Jupiter is the oldest planet in the solar system. This planet, which is 2.5 times heavier than the rest of the planets in the solar system, has played an important role in the formation and evolution of its neighbors. 4.6 billion years ago, the solar system was a cloud of gas and dust or the solar nebula. Gravity caused this material to collapse and begin to rotate; The sun was born in its center. As the sun formed, the rest of the material condensed. Small particles were brought close to each other by the force of gravity and turned into larger particles.

The solar wind blew away lighter elements like hydrogen and helium, and heavier rocky material near the Sun formed smaller rocky worlds like Earth. Since the solar wind had less effect on the lighter elements, these elements joined together to form gas giants.

According to the core accretion model, the rocky cores of the planets were formed first, then the lighter elements formed the mantle and the crust of the planets. On rocky worlds, the lighter elements formed the atmosphere. Examination of exoplanets (outside the solar system) supports the core accretion theory as the dominant formation process. Stars with more metal in their cores (a term astronomers use for elements other than hydrogen and helium) have larger planets in their systems than stars made only of metal.

The core accretion process for gas giants like Jupiter takes a long time. The cloud of matter around the sun lasts only a short time; It either becomes a planet or disappears completely. Giant planets, unlike rocky planets such as Mars and Earth, formed very quickly and only in a few million years. As a result, based on a certain period of time, the gas ring around the sun lasted only 4 to 5 million years.

According to a relatively new theory called disc instability, masses of gas and dust joined together early in the life of the solar system. Over time, these masses turned into larger planets. The speed of formation of these planets based on this theory is faster than the core accumulation theory and sometimes even reaches several thousand years. Constant collisions in Jupiter (just like other planets) raised the temperature of this planet. Dense material moved towards the center and formed the nucleus. Some scientists believe that the core of this planet can be a hot ball of liquid; While according to other researchers, Jupiter’s core is a solid rock with a size of 14 to 18 times that of Earth.

Gravel accumulation

The biggest challenge of nuclear accretion theory is its time. According to another study, small pebble-sized objects joined together to form large planets at a rate 1,000 times faster than previous models. In 2012, two researchers named Michel Lambrecht and Anders Johansen from Lund University in Sweden presented the theory of small particles. Based on their analysis, pebbles left over from formation processes (which were previously considered insignificant) could hold the key to the problem of planet formation.

Customer relocation

In 2011, scientists unveiled the Grand Tack model. According to this theory, the customer had a two-stage migration after forming. Jupiter was formed exactly at a distance of 3.5 AU from the Sun, and after a two-stage transition, it is at its current position of 5.2 AU.

Jupiter is thought to have destroyed many objects during these transits, including some of the first-generation planets of the solar system. Without Jupiter, there would probably be no Earth; This planet has cleared the way for Earth by destroying smaller worlds.

Jupiter is how much bigger than Earth?

If we add the mass of all the planets of the solar system together, the mass of Jupiter will be more than twice that. This gas giant can accommodate 1300 planets. As a result, if you consider the planet Jupiter to be the size of a basketball, the Earth will be the size of a grape seed. This gas planet is also 318 times heavier than Earth. In the diameter of Jupiter, you can fit 11 planets.

Planet Earth against Jupiter; Jupiter contains more than 1300 lands

Physical characteristics and internal composition of the planet Jupiter

A large part of Jupiter consists of liquid and gaseous materials. The diameter of this gas giant reaches 142,984 km. Its average density is 1326 grams per cubic centimeter, and in this respect, it ranks second among gas giants. A large part of Jupiter consists of gaseous and liquid materials, and denser materials are located in the lower layer. 88-92% of the upper atmosphere of this planet is made up of hydrogen and 8-12% of it is made up of helium. Generally, 75% of the mass of this planet is hydrogen, 24% is helium and the remaining 1% are other elements.

Jupiter’s atmosphere contains amounts of methane, water, steam, ammonia, and silicon compounds. Traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur can also be seen in it. The outermost layer of the atmosphere consists of frozen crystals of ammonia. The material density is higher in the inner layers. The discovery of water on the planet Jupiter was one of the interesting discoveries of the past years. Using the Juno probe, scientists have found evidence of water on the planet Jupiter, which is far beyond their imagination.

Using ultraviolet and infrared measurements, amounts of benzene and hydrocarbons have also been discovered on this planet. According to the spectroscopic results, the composition of Jupiter is almost the same as that of Saturn; But the other two gas giants, Uranus and Neptune, have less hydrogen and helium and more ice than Jupiter, and hence they are also called ice giants.

Jupiter can hold 1,300 Earths

Based on gravity measurements in 1977, the mass of the core of this planet was estimated to be 12 to 45 times greater than the mass of Earth. Jupiter’s core makes up 4-14% of its total mass. The radius of Jupiter is approximately one-tenth of the radius of the Sun and the mass is one-thousandth of the mass of the Sun; Therefore, the density of both is the same. Jupiter’s mass is commonly used as a unit to describe the mass of other objects, especially exoplanets or brown dwarfs.

If Jupiter were 75 times heavier, it would have the possibility of hydrogen fusion and become a star; Meanwhile, the radius of the smallest red dwarf is only 3% more than Jupiter. However, Jupiter emits more heat than it receives from the sun.

The amount of heat produced by Jupiter is equal to the total solar radiation received by this planet. This process causes Jupiter to become smaller by 2 cm every year. While it was much hotter at the beginning of its formation its diameter was twice its current diameter. According to existing hypotheses, the core of Jupiter is rocky; But its exact composition is still unknown. The core may be surrounded by dense metallic hydrogen, which makes up 78% of the planet’s radius. Raindrops such as helium and neon are deposited towards the bottom of this layer and the abundance of these elements in the upper atmosphere is minimized.

Customer core
This cut shows a model of Jupiter’s interior with a rocky core surrounded by a deep layer of liquid metallic hydrogen.

Like the Sun’s atmosphere, most of Jupiter’s atmosphere consists of hydrogen and helium. The dark and light-colored bands on Jupiter’s atmosphere are caused by strong east-west winds that move at a speed of more than 539 kilometers per hour. Clouds in bright areas are composed of frozen crystals of ammonia; While clouds in darker areas are made up of other chemicals. In the deepest observable level of this planet, there are blue clouds. Jupiter’s cloud bands change over time and rain diamonds within Jupiter’s atmosphere.

It is hard to say what exactly Jupiter’s atmosphere is made of because 90% of this planet is hydrogen and 10% is helium. On Earth, all these gases are considered atmospheric; But the strong gravity of Jupiter causes the atmosphere of this planet to become several separate layers, each of which has attractive and unique characteristics. Unlike Earth, there is no clear boundary between Jupiter’s atmosphere and the planet itself. By penetrating further into the depths of Jupiter, the density and temperature of hydrogen and helium change, and based on these changes, scientists describe the different layers of Jupiter’s atmosphere. Jupiter’s atmospheric layers include the troposphere, stratosphere, thermosphere, and exosphere.

Since Jupiter does not have a solid surface, scientists estimate the pressure of the lower part of its atmosphere to be 100 kilopascals; The planet’s atmosphere is defined just above this point. Like Earth’s, Jupiter’s atmosphere decreases with altitude until it reaches its minimum value. The minimum amount of atmosphere can be found at the boundary between the troposphere and stratosphere, the tropopause (approximately 50 km above the surface of Jupiter).

The stratosphere extends up to a height of 320 km, and along that line, the pressure decreases, as the pressure decreases, the temperature increases. At this point, the boundary between the stratosphere and the thermosphere is defined. The temperature of the thermosphere reaches 726 degrees Celsius at an altitude of 1000 kilometers. All visible clouds and storms are located in the lower troposphere of Jupiter and are composed of ammonia, hydrogen sulfide, and water.

Jupiter’s Great Red Spot

The most obvious feature of Jupiter is its big red spot. This spot is a persistent larger-than-Earth cyclonic storm located at an angle of 22 degrees to the equator, which was discovered based on one hypothesis from 1831 and another from 1665. This spot is large enough to be easily seen with an amateur telescope with an aperture of 12 cm. The rotation direction of this tornado is anti-clockwise and its circulation period is 6 days. The maximum height of this storm is 8 km above the cloud area.

According to mathematical models, this storm is stable and may be one of the stable features of this planet. However, the size of this spot has always decreased. In the late 1800s, the width of this spot was estimated to be about 56,327 km, which is four times the diameter of the earth. After the Voyager 2 spacecraft reached this planet in 1979, the diameter of this storm had decreased to twice the width of the planet Earth.

Reviews of Jupiter’s red spot show that the spot is still shrinking in size. On April 3, 2017, the width of this spot was estimated to be 16,350 km, which is 1.3 times the diameter of the Earth. Earth’s longest storm lasts 31 days, But Jupiter has more stable storms due to having thousands of kilometers of atmosphere at a speed much faster than the Earth’s rotation.

red spot
Jupiter’s Great Red Spot has shrunk over the years.

Jupiter’s magnetic field

Jupiter’s magnetic field is fourteen times stronger than Earth’s magnetic field. This field is thought to be created by eddy currents in the metallic hydrogen core of this planet. Some features of Jupiter’s magnetic field are unique and do not exist in Earth’s magnetic field.

The volcanoes of Jupiter’s moon Ivy release large amounts of sulfur dioxide, resulting in a gas halo around the moon’s orbit. This gas is ionized in Jupiter’s magnetosphere and sulfur and oxygen ions are released.

These ions together with the hydrogen ion of Jupiter’s atmosphere form a plasma sheet in the equatorial body of this planet. The plasma in this sheet rotates with the planet and leads to the change of the bipolar magnetic field into a magnetic disk. The electrons in the plasma sheet create a strong radio effect that produces bursts in the 0.6 to 30 MHz range.

Jupiter’s magnetosphere is responsible for the intense emission of radio material from the polar regions of this planet. Volcanic activities of this planet’s moon Ivy lead to the release of gas in Jupiter’s magnetosphere and create a halo of particles around it. As Io moves in this halo, Alphon waves are created. An Alfón wave is a type of magnetohydrodynamic wave in which ions oscillate along magnetic field lines in response to an effective voltage. These waves carry ionic material in Jupiter’s polar regions.

Rotation and orbit of Jupiter

The average distance between Jupiter and the Sun is 778 million kilometers (about 5.2 times greater than the distance between the Earth and the Sun) and the Earth orbits the Sun every 11.86 years. Compared to Earth, Jupiter’s elliptical orbit has a deviation of 1.31 degrees. The eccentricity of this planet’s orbit is 0.048, which is why its distance from the Sun varies between the closest contact (perigee) and the farthest distance (apex) as much as 75 million kilometers.

The axial tilt of this planet is relatively small: 3.13 degrees. As a result, it does not have many seasonal changes compared to Earth and Mars. Jupiter rotates the fastest among the planets of the solar system and completes its rotation around its axis in less than ten hours. Due to the high speed of rotation, an equatorial bulge is created, which is easily visible through an amateur telescope located on Earth. The diameter of Jupiter’s equator is 9275 km more than the diameter of its poles. Because Jupiter is not a solid body, its upper atmosphere has a different rotation. Jupiter’s polar atmosphere rotates approximately 5 minutes longer than its equatorial atmosphere.

How many moons does Jupiter have?

Jupiter has 79 confirmed moons. In terms of the number of moons, Jupiter ranks second in the solar system after Saturn (with 82 moons); But according to the latest research, Canadian astronomers found evidence of the existence of 45 small moons in the orbit of Jupiter, and based on speculations, the number of moons of this planet can reach 600; But they have not yet reached the verification and monitoring stage.

Overall, among Jupiter’s 79 confirmed moons, the four largest Galilean moons are the most prominent. These moons were discovered independently by Galileo Galilei and Simon Marinus in 1610. As early as 1892, more moons of Jupiter were discovered and named after the lovers or daughters of Jupiter, the Roman god, or Zeus (his Greek counterpart). The Galilean moons are the largest and heaviest objects in Jupiter’s orbit.

Jupiter’s eight moons are regular moons with nearly circular orbits. The Galilean moons are nearly spherical due to their planetary mass. If these moons were in the orbit of the sun, they would be classified as dwarf planets. The other four moons are smaller and less distant from Jupiter; These moons are sources for the formation of Jupiter’s rings. Other moons of Jupiter are irregular and their orbits are further away from Jupiter. These moons are probably trapped by Jupiter’s gravity from the solar orbits. Jupiter’s twenty-two irregular moons have yet to be officially named.

Jupiter’s regular moons are thought to have formed from the planet’s rotating disk; A ring of gas and rock similar to a primordial planetary disk. On the other hand, irregular moons are composed of asteroids that are caught in the trap of Jupiter’s gravity. According to many scientists, these asteroids were crushed and then formed the irregular moons of Jupiter due to impact with other small bodies.

Group of moons

In general, Jupiter’s moons are divided into two categories: regular and irregular. Irregular moons are divided into two groups: internal moons (Amaltia) and Galilean moons.

  • Internal moons (Amaltia): Metis, Adrastia, Amaltia, and Thebe are internal moons of Jupiter; Because they are in close proximity to this planet. Two of the innermost moons complete the orbit of Jupiter in less than a day. The other two moons are the fifth and seventh largest moons in Jupiter’s lunar system, respectively. According to observations, at least the largest member of this group, Amaltia, did not form on the current orbit, but was already further away from Jupiter.
  • The main group of Galilean moons: Io, Europa, Ganymede, and Callisto are among the largest moons in the solar system in terms of mass and size. The diameter of the moon Ganymede is even greater than the planet Mercury, but its mass is less. These moons are the fourth (Io), sixth (Europa), first (Ganymede), and third (Callisto) natural moons of the solar system, respectively, and comprise approximately 99.997% of the total mass of Jupiter’s orbit. Jupiter is 5000 times heavier than its moons.

Irregular moons of Jupiter

Irregular moons of Jupiter are small bodies with eccentric orbits and further away from Jupiter. These moons have similarities such as declination, eccentricity, semimajor axis, and chemical composition. According to scientists, these are a group of impact moons that were formed by the collision of larger parent objects with asteroids caught in Jupiter’s gravitational field.

Galilean moons

The Galilean moons are among the most well-known moons of Jupiter that have been studied by various probes and more information is available. In the following, we mention the features and explorations related to these moons.

Moon Io

Io is the fifth largest moon of Jupiter and has the most volcanic activity in the solar system. This moon has sulfur channels that spread up to 300 km. Io’s surface is filled with lava seas and liquid rock floodplains. Astronomers discovered a map of 150 volcanoes on this moon, some of which emit lava up to 400 kilometers into space. At 4.5 billion years old, Io is the same age as its host planet Jupiter. The average orbital distance between Io and Jupiter is 442 thousand km. It takes 1.77 Earth days for Io to complete an orbit around Jupiter. Io has a tidal lock and always has one side facing Jupiter. The diameter of Io is approximately 1,820 km, which is slightly more than the diameter of the Moon.

Io is the only moon in the solar system with active volcanoes

Io has a relatively oval shape. Among the Galilean moons, Io ranks lower than Ganymede and Callisto in terms of mass and volume and ranks higher than Europa. The average surface temperature of Io is minus 130 degrees Celsius. For this reason, sulfur dioxide snow bodies are abundant on its surface. Io is also called the moon of ice and fire.

Io was discovered on January 8, 1610, by Galileo Galilei. He actually discovered this moon the day before, But he could not distinguish Io ​​and Europa. Galileo’s discovery was the first lunar discovery at that time. Galileo’s discoveries proved that the planets revolve around the sun, not the earth. Galileo initially named this moon Jupiter 1; But in the middle of the 19th century, its name was changed to Ayo. In Greek mythology, Io was the priestess of Hera (wife of Zeus) and the daughter of Inachus, king of Argos. Zeus (the Greek counterpart of the Roman god Jupiter) fell in love with Io, But he turned him into a cow to protect him from his wife Hera.

IO features: IO’s interior consists of an iron sulfide core and a brown silicate outer layer. This combination has given this moon a mottled appearance with orange, black, yellow, red, and white colors. Based on data obtained from computer models, Io formed in a region around Jupiter where the abundance of ice was initially high. The heat of Io along with the water on its surface shortly after its formation can be a sign of the existence of ancient life; Even in an environment where Jupiter’s radiation destroys surface water.

The most prominent features of this moon are its volcanoes. After Earth, Io is the only body in the solar system with active volcanoes. Galileo made notes of volcanic activity, and NASA’s Voyager spacecraft confirmed Io’s volcanoes in 1979. Due to volcanic activity, a large part of the atmosphere is sulfur dioxide. Based on observations from the Gemini North telescope in Hawaii and the TEXES spectrometer in 2018, Io’s atmosphere is likely to collapse. Io’s sulfur dioxide gas mantle freezes in shadow every day. When Io returns to sunlight, the frozen sulfur dioxide turns into a gas once more.

Moon Io

Callisto is one of the large moons in the orbit of Jupiter. This moon has an ancient surface full of impact craters, which shows that there is no news of geological processes in it; But this moon has an underground ocean and because of its old surface, the existence of life in this ocean is still not certain.

Callisto, like the other four Galilean moons, was discovered in 1610. The name of this moon was originally Jupiter IV, But in the 19th century, it was called Callisto. Callisto was studied by several probes, including the long-duration mission of the Galileo spacecraft to Jupiter in the 1990s and 2000s. The Juno spacecraft has also recorded remote images of the moon Callisto. At 4.5 billion years, Callisto is the same age as its host planet, Jupiter. This moon is the heaviest body with an impact hole in the entire solar system, But its surface has remained untouched since almost 4 billion years ago.

Among the Galilean moons, Callisto is the outermost. This moon is located at a distance of one million eight hundred and eighty thousand kilometers from Jupiter. Callisto takes approximately seven Earth days to complete an orbit of Jupiter. Callisto has fewer tidal effects than the other Galilean moons; Because on the other side of Jupiter’s main radiation belt is located. Callisto is tidally locked to Jupiter and always faces Jupiter on one side.

With a diameter of 4800 km, Callisto is almost the same size as the planet Mercury. This moon is the third largest moon in the solar system after Ganymede and Titan (Saturn’s moon). Moon is placed in fifth place after Io. Callisto’s surface temperature reaches minus 139.2 degrees Celsius. In 1996, the Galileo spacecraft sent back detailed information about Callisto. The mission mapped much of the moon’s surface and discovered its thin carbon dioxide atmosphere and evidence of a subsurface ocean. Callisto’s effect on the auroral bursts of Jupiter’s atmosphere has been revealed based on a review of images obtained from the Hubble Space Telescope in 2018. The client himself has an aura, But some of Jupiter’s aurora phenomena originate from interactions with its four large moons.

Future missions, including JUICE, which will investigate Jupiter’s icy moons, will reveal more about Callisto and the possibility of life there. Papers have also been published on modeling the interaction of Jupiter’s magnetic field with Callisto (this review provides evidence for Callisto’s subsurface ocean) and finding atomic oxygen in the moon’s atmosphere. Other papers have focused on dimensions such as subsurface water, the number of impact craters, and atmospheric properties.

Callisto's moon

Ganymede is the largest moon of Jupiter and the largest moon in the entire solar system. This moon is even bigger than Mercury and Pluto and slightly smaller than Mars; As a result, if it was in the orbit of the sun, it would easily be classified as a planet. Ganymede probably has a saltwater ocean beneath its icy surface; As a result, it becomes one of the strong candidates for life discoveries. Ganymede is one of the targets of the JUICE mission, which will be launched in the 2030s.

The three moons of Callisto, Ganymede, and Europa have subsurface oceans of saltwater

Like Callisto and Io, Ganymede is the same age as Jupiter at 4.5 billion years old. This moon is more than one million and seventy thousand kilometers away from Jupiter and completes the orbit of this planet in seven days. The average radius of Ganymede is 2631.2 km. Ganymede is larger than Mercury, but its mass is half that of Mercury, and as a result, it has a low density. The average daytime temperature on the surface of Ganymede reaches minus 113 to minus 183 degrees Celsius. Astronomers with the Hubble telescope found evidence of Ganymede’s thin oxygen atmosphere in 1996. However, this atmosphere is too thin to support life as we know it, and it is unlikely that life could inhabit Ganymede.

Ganymede is the only moon with a magnetosphere in the entire solar system. A magnetosphere, commonly seen on planets like Jupiter and Earth, is a comet-shaped region where charged particles are trapped and deflected. Ganymede’s magnetosphere is embedded in Jupiter’s magnetosphere. After Galileo discovered Ganymede, he renamed it Jupiter III. With the increase in the number of objects discovered in the middle of the 19th century, the name of this moon was changed to Ganymede based on Greek mythology.

Features of Ganymede: Ganymede has an iron core, a rocky mantle, and a very thick crust, most of which is made up of ice. Also, traces of rock formation can be seen on the surface of Ganymede. In February 2014, NASA unveiled a detailed map of Ganymede in the form of images and video animation, created using observations from NASA’s Voyager 1 and 2 spacecraft as well as the Galileo orbiter.

Ganymede’s surface consists of two main surface types: approximately 40% of Ganymede’s surface is dark with numerous impact craters, and 60% is light-colored with grooves that give Ganymede its distinctive appearance. Grooves are caused by tectonic activities or subsurface water release.

According to scientists, Ganymede has an underground saltwater ocean. In 2015, scientists used the Hubble Space Telescope to study Ganymede’s auroras and the changes between the magnetic fields of Jupiter and Ganymede. Based on the evidence of these auroras, Ganymede probably has a subsurface ocean of saltwater that is even saltier than Earth’s oceans.

Some scientists have pointed to the possibility of life on Ganymede. Because of Ganymede’s internal structure, the pressure on the ocean floor is so high that any water that reaches it turns into ice. For this reason, hot water currents can hardly deliver nutrients to the oceans.


Europa is the smallest Galilean moon. The surface of this moon is frozen and covered with a layer of ice; But according to scientists, there is an ocean under this ice surface. The icy surface makes Europa one of the most reflective moons in the solar system.

Using the Hubble Space Telescope, researchers detected signs of geysers from the Antarctic region of Europe in 2012. After several attempts, another research team observed the geysers in 2014 and 2016. Europa’s moon formed at the same time as its host planet, Jupiter, about 4.5 billion years ago. On average, the distance between Europe and Jupiter is 670,900 kilometers. It takes Europa three and a half Earth days to complete an orbit of Jupiter. Europe has a tidal lock to Jupiter; Therefore, one side is always facing the customer.

With a diameter of 3100 km, Europa is smaller than the Moon and larger than Pluto. The temperature of Europe’s surface at the equator never rises above minus 160 degrees Celsius, and at the poles of this moon, it never rises above minus 220 degrees Celsius. Galileo discovered the Europa moon on January 8, 1610. Of course, he had observed it the day before on January 7; But he could not distinguish this moon from Io. In Greek mythology, Europa is stolen by Zeus (a counterpart of Jupiter, the Roman god) and takes the form of a white bull to seduce Europa. He decorates the cow with flowers and sends it to the city of Crete. Zeus returns to his normal form in Crete and seduces Europa. Europa was the queen of Crete and bore Zeus several children.

One of the prominent features of Europa is its high reflectivity due to its ice crust. According to scientists’ estimates, the surface of Europe is 20-180 million years old. Images and data from the Galileo spacecraft show that Europa has a composition of silicate rock, an iron core, and a rocky mantle just like Earth. Unlike the Earth’s interior, Europa’s rocky atmosphere is surrounded by a layer of water or ice, which is 80 to 170 km thick. Based on the fluctuations of Europa’s magnetic field, there is probably an ocean beneath the moon’s surface that could host life. The possibility of extraterrestrial life has made Europa an attractive destination for space exploration.

The surface of Europe is full of cracks and fissures. According to many scientists, these cracks are the result of the tidal forces of the ocean beneath Europa’s surface. As Europa approaches Jupiter, sea levels below the ice rise above normal. In this situation, the continuous tide of the sea causes cracks in the surface of this moon. In 2014, scientists discovered that Europa could host tectonic plates. In the solar system, only the Earth has a variable crust, which is useful for the evolution of life on Earth.

Life in Europa: The presence of water under the frozen crust has made Europa’s moon one of the possible candidates for hosting life in the solar system. The icy depths of this moon probably have channels to the mantle like Earth. These channels provide the warm environment necessary for the evolution of life. According to a 2016 study, Europa’s oxygen content was estimated to be ten times that of hydrogen, similar to that of Earth. Thus, the ocean under the surface of Europe becomes a better environment for life.

Europa's moon
Europa, a moon of Jupiter

Customer rings

Maybe for many people this question has arisen, why the planet Jupiter does not have rings like Saturn? In fact, Jupiter has rings, but since Jupiter’s rings are made of rock and dust, and Saturn’s rings are made of rock and ice, Jupiter’s rings do not appear as bright as Saturn’s rings. Jupiter’s rings are divided into three parts: halo, main ring, and thin ring. Jupiter’s rings were discovered by the Voyager probe in 1980. The composition of Jupiter’s rings is different from that of Saturn, which is composed of ice. Jupiter’s rings are very faint and delicate.

  • Halo section: The innermost part of Jupiter’s rings, which is made up of dust and surrounds the space around the planet. This is the brightest and thickest part of Jupiter’s rings.
  • The main ring section: The main ring section is the narrowest part and consists of dust and gravel. The age of dust particles in this section reaches 1000 years or even 100 years. This means new dust is formed due to impact with larger rocks.
  • Thin Outer Ring (Gossamer): Gossamer is the outermost part of Jupiter’s rings. This part, like the previous two parts, is a combination of dust particles; But the word Gossamer means thin material, which is suitable for this part because of the very small dust particles.

Only the most powerful telescopes are capable of observing Jupiter’s rings. Jupiter’s moons are responsible for the formation of the rings of this planet. The innermost moons, such as Amaltha, Adrasta, and Tibe, were hit by many meteorites, and their dust and rock particles entered Jupiter’s orbit, thus forming the rings of this planet.

Wonders of Jupiter

The planet Jupiter has many surprises due to its strong gravity and magnetic field, as well as its strange moons. Below are some examples of these surprises:

The effect of Jupiter on the solar system: Jupiter is also known as the vacuum cleaner of the solar system due to its strong gravity and internal position of the solar system. This planet experienced the most collisions with comets among the planets of the solar system and thus it is thought to act as a shield for the inner planets of the solar system.

If Shoemaker’s comet Levi 9 collided with Earth, there would be no trace of life left on Earth.

However, based on recent computer simulations, Jupiter has not played a significant role in reducing the bombardment of the inner planets of the solar system, although the debate on this issue is still ongoing. At least it saved the inner planets from a catastrophe called Shoemaker Levi 9. Comet Shoemaker Levi 9 has experienced one of the most exciting endings. Shoemaker Levy’s collision with Jupiter left scars on the planet’s surface that are visible even from Earth. This is the first collision of two internal bodies in the solar system, and the effects of this comet on Jupiter’s atmosphere are spectacular and beyond expectations.

Shoemaker’s comet Levi 9 collided with Jupiter in 1994, and this collision caused a lot of fear among the public because if a similar comet hit the Earth, life on the planet would be completely destroyed.

Effects of comet Shoemaker Levi 9 impact on Jupiter

Two movies, Armageddon and Deep Encounter, were inspired by this encounter and were made with the theme of Earth-threatening objects. After the release of these videos, Congress asked NASA to search for near-Earth objects. Shoemaker Levi 9 was first discovered in March 1993 by comet explorers Eugene and Carolyn Shoemaker and David Levi. The group had previously collaborated several times and discovered other comets. For this reason, the name Shoemaker Levi 9 was chosen for this comet.

This comet had been orbiting Jupiter decades before, in 1966, but it had not been trapped by the planet’s strong gravity. Orbital calculations further indicated that this comet collided with Jupiter in July 1994. At that time, the Galileo spacecraft was still en route to the planet and could not capture a close-up view of the encounter.

Strange auroras: This year, the Juno probe discovered new auroras that oscillate over Jupiter’s poles. Juno’s Ultraviolet Spectrometer (UVS) instrument recorded this bright phenomenon. These auroras expand in the form of rings with a high speed between 3.3 and 7.7 km/s. According to scientists, these auroras are caused by charged particles from the edge of Jupiter’s huge magnetosphere. Jupiter’s auroras, like Earth’s, depend on the charged particles of the magnetosphere. However, Jupiter’s magnetosphere is 2000 times stronger than Earth’s magnetosphere.

Hubble telescope image of Jupiter’s auroras

New facts about Jupiter’s hot spots: A generation after discovering Jupiter’s hot, dense atmosphere, the Juno mission has new answers about these spots. Juno discovered hot spots that were much wider and deeper than past models and observations. These results were announced on December 11, 2020, at the annual conference of the American Geophysical Union.

More water discovered in Jupiter’s atmosphere: According to data from the 2020 Juno probe, approximately 0.25 percent of the molecules in Jupiter’s equatorial atmosphere are water molecules. Although this amount does not seem much, based on the calculations of water components, hydrogen and oxygen in Jupiter are three times more than the water molecules of the Sun. Juno’s measurements discovered more water than previous missions. This discovery could help scientists in their search for the true origin of Jupiter.

The similarity of Jupiter’s wavy atmosphere to Earth’s clouds: Jupiter and Earth may seem like two completely different planets, but the atmospheres of these two planets are more similar than they seem. In 2018, the Juno probe captured images of small-scale wave patterns in Jupiter’s atmosphere. These images, captured by the JunoCam instrument, reveal the similarity of these cloud shapes to Earth. These waves in the Earth’s atmosphere are called mesoscale or medium-scale waves. Now, similar waves have been discovered in Jupiter’s atmosphere, which are called atmospheric waves.

In this image taken by NASA’s Juno spacecraft, the shape of Jupiter’s atmospheric clouds resembles a tornado on Earth.

Seeing Jupiter from Earth

Jupiter is the fourth brightest object in the night sky (after the Sun, Moon, and Venus). Depending on Jupiter’s position relative to the sun and the Earth, its range of vision varies. The average visibility range of this planet is minus 2.20 and its standard deviation is 0.33.

Since the orbit of Jupiter is outside the Earth, the phase angle of this planet from the Earth never exceeds 11.5 degrees. For this reason, this planet is always seen brightly from telescopes on the ground. With a small telescope, you can even observe the Galilean moon and the cloud belts around Jupiter’s atmosphere.

Pre-telescopic researches

Jupiter’s observation dates back to Babylonian astronomers in the 7th or 8th century BC. Chinese astronomers also observed the orbit of Jupiter and based on the approximate number of years, they made its 12-branched terrestrial cycle. Ground-based telescopic research

In January 1610, Galileo Galilei examined the planet Jupiter with his small telescope. His observations changed the current understanding of the universe. Galileo observed three small stars near Jupiter. The next afternoon, he was able to see the stars again, but this time they were on the other side of the planet. Over the course of several weeks of observation, these stars moved around Jupiter. Galileo gave the name of Medici’s stars to these objects out of gratitude to his patron Cosmo de’ Medici, but today they are known as Galileo’s moons.

This observation was the first telescopic observation of the moons of the solar system (other than the Earth’s moon). A day after Galileo, Simon Marinus independently discovered the moons around Jupiter, but he did not publish the results of his discoveries until 1614. This discovery was a turning point in Copernicus’ heliocentric theory of planetary motion. Galileo was prosecuted for blasphemy for supporting this theory.

Giovanni Cassini
Giovanni Cassini

In the 1660s, Giovanni Cassini used a new telescope to discover Jupiter’s colorful bands and spots and was able to estimate the planet’s rotation period. In 1690, Cassini realized the difference between the rotation of Jupiter’s atmosphere and the planet itself. Probably, the Great Red Spot in the southern hemisphere of Jupiter was observed in 1664 by Robert Hooke and in 1665 by Cassini, although there is still a debate on this issue. Astronomer Henrich Schwab published the first detailed sketch of the Great Red Spot in 1831.

Both Giovanni Beverley and Cassini made detailed tables of Jupiter’s lunar motions, and based on that, they used to predict the motions of these moons. In 1892, E.E. Barnard discovered the fifth moon of Jupiter at Lake California Observatory. The discovery of this relatively small object made him famous. This moon was named Amalatha. It was the last planetary moon to be discovered directly by visual observation.

In 1932, Robert Wildt discovered the bands of ammonia and methane. Three gyres (large-scale rotation of wind around a central point of high atmospheric pressure counterclockwise) called white rings were also discovered in 1938. Finally, two rings were merged in 1998 and the third ring known as BA was absorbed in 2000.

Radiotelescopic researches

In 1955, Bernard Burke and Kenneth Franklin managed to detect bursts with a power of 22.2 MHz based on radio signals. The period of these bursts coincided with the rotation of the planet, and they used this information to correct the rotation ratio. Jupiter’s radio bursts come in two main forms: long bursts (L bursts) lasting up to several seconds, and short bursts (S bursts) lasting less than a hundredth of a second.

Jupiter probes

So far, eight spacecraft and probes have explored Jupiter: Pioneer 10 and 11, Voyager 1 and 2, Galileo, Cassini, Ulysses, New Horizons, and Juno.

Pioneer 10 and 11 (Pioneer)

Pioneer 10 and 11 were the first spacecraft to explore Jupiter. These two probes recorded the first scientific observations of Jupiter and Saturn, paving the way for the Voyager missions. The external instruments of these spacecraft investigated the atmospheres of Jupiter and Saturn, magnetic fields, moons, and rings, as well as interplanetary dust and magnetic regions, solar winds, and cosmic rays. These two probes continued their journey and left the solar system.

Pioneer 10
Picture of Pioneer 10 from Jupiter

Voyager 1 and 2

NASA sent two Voyager spacecraft to Jupiter, Saturn, Uranus, and Neptune in the late summer of 1977. Voyager 1’s closest contact with Jupiter was recorded on March 5, 1979. Voyager 2’s closest approach to this planet was recorded on July 9, 1979.

Jupiter photography began in January 1979. Voyager 1 completed its mission to Jupiter in early April after recording 19,000 images and many other science measurements. Voyager’s mission period was from late April to early August. The two spacecraft captured more than 33,000 images of Jupiter and its five moons. Voyager 1 and 2 provided researchers with a lot of information about moons, magnetic fields, and more. The biggest achievement of these two spacecraft was the discovery of active volcanoes on Io’s moon.

Voyager 1 image of Jupiter

Galileo Spacecraft

The Galileo spacecraft was launched on October 18, 1989, by the space shuttle Atlantis and reached Jupiter in 1995. This probe spent almost eight years in the orbit of Jupiter and studied its moons. Based on the information obtained from the camera and nine other instruments of this probe, the possibility of an ocean under the surface of Europa’s moon was investigated. According to the discoveries, the volcanoes of Io’s moon are very active. One of Galileo’s other discoveries was the distinct magnetic field of Ganymede. Galileo was carrying a small probe that was sent deep into Jupiter’s atmosphere, and about an hour later it was destroyed by high pressure.

Cassini spacecraft

Cassini was a joint collaboration between NASA the European Space Agency (ESA) and the Italian Space Agency, and its main objective was to study Saturn, its ring system, and its moons. The probe made its closest approach to Jupiter on December 30, 2000, and recorded numerous scientific measurements. Cassini captured 26,000 images of the planet, its rings, and moons during its six-month flyby around Jupiter. Cassini’s greatest achievement of Jupiter was capturing the most detailed color portrait of the planet (up to that time).

Among other Cassini observations, we can mention a dark swirling cloud in the upper part of Jupiter’s atmosphere, which was almost the same size as the Great Red Spot and is located near its north pole. Based on the evidence that Cassini obtained from Jupiter’s rings, this ring is composed of irregularly structured objects that were probably formed by the disintegration of rock from the moons Metis and Adrasta.

Ulysses spacecraft

Ulysses was the result of the joint collaboration of NASA and the European Space Agency, which was launched in October 1990, and its main purpose was to study the space region above the poles of the Sun. Since Ulysses needed a lot of energy to orbit the Sun and the Earth was unable to provide this energy, it was necessary for this spacecraft to obtain its energy from another planet. Jupiter was the closest planet that could provide the prerequisites for this journey.

Ulysses reached Jupiter 16 months after separation from Earth and made its closest approach to the planet on February 8, 1992. Although the secondary purpose of Ulysses was to study Jupiter, in this short trip he was able to obtain very useful information about the very strong magnetic field of this planet.

New Horizons spacecraft

New Horizons was an interplanetary probe built at the Johns Hopkins University Physics Laboratory (APL) and Southwest Research Institute (SwRI) and launched in 2006 to study Pluto. New Horizons used Jupiter’s gravity (320 times that of Earth) to orbit Pluto.

New Horizons used the LORRI instrument to record its images of Jupiter on September 4, 2006, from a distance of 291 million kilometers from the planet. Closer examination of Jupiter continued in January 2007 with an infrared image of Callisto’s moon and several black-and-white images of Jupiter itself.

One of the main goals of this probe was to investigate atmospheric conditions and analyze the structure of Jupiter’s clouds. For the first time, this probe was able to record close-up images of Jupiter’s small red spot. He also managed to capture images of the ring system of the planet from different angles. New Horizons captured valuable information on Jupiter’s magnetosphere as it traveled towards it.

Juno spacecraft

NASA’s Juno spacecraft was launched on August 5, 2011, and entered Jupiter’s orbit on July 5, 2016, to begin detailed scientific studies of the planet. So far, this spacecraft has orbited Jupiter 32 times and spent almost a year at a distance of 5,000 km above Jupiter’s clouds.

The purpose of the Juno mission is to measure the composition, gravitational field, magnetic field, and polar magnetosphere of this planet. It also looks for clues about how the planet formed, its rocky core, the amount of water in the deep atmosphere, its mass distribution, and its deep winds, which reach speeds of up to 610 kilometers per hour.

Unlike other probes sent to the planets of the Solar System, Juno is powered by solar arrays similar to Earth satellites, while radiative isotope thermoelectric generators are typically used for intrasolar system missions.

Some images recorded by the Juno probe since 2016

During Juno’s mission, its infrared and microwave instruments will measure thermal radiation from Jupiter’s atmosphere. These observations are complementary to previous investigations of the planet’s composition regarding the abundance and distribution of water and oxygen. Data provides new insights into customer origin.

Juno also made unprecedented findings about Jupiter’s atmospheric winds. Based on these findings, the atmospheric winds of this planet last longer than the atmospheric processes on Earth. Juno’s measurements of Jupiter’s gravitational field confirm the planet’s north-south asymmetry, which is similar to the asymmetry observed in the planet’s belts and bands. As the winds get deeper, their mass increases.

According to one of Juno’s other findings, there is a solid body under the weather layer of this planet. This result is surprising, and future Juno measurements will help to understand this transition from the air layer to the solid body. Before the Juno discoveries, there was no information about the atmosphere near Jupiter’s poles. According to the data obtained from this probe, Jupiter’s poles are rougher in nature compared to the more familiar white and orange belts located in the planet’s lower latitudes.

The north pole of this planet is surrounded by a central cyclone, which itself is surrounded by eight far-polar cyclones with diameters varying from 4000 to 46000 km. Jupiter’s south pole also has a central tornado that is surrounded by five other tornadoes with diameters ranging from 5,600 to 7,000 km. The Juno spacecraft is currently surveying Jupiter from the planet’s orbit, sending back stunning images, atmospheric data, and other observations about the planet.

Images by James Webb of Jupiter

The James Webb Space Telescope, which has been operating since last year, has made impressive observations in the last few months. One of these remarkable observations is the detailed images of the planet Jupiter and its auroras. Both images of this telescope are composites, that is, they are made from the combination of several images that were taken with the telescope’s near-infrared camera (NIRCam) and photographed with different filters.

A composite image of Jupiter captured by the NIRCam camera shows the planet’s rings and its two moons, Amalthea and Adrastia. The blue halo around Jupiter’s poles are the auroras.

In the wider image, you can see Jupiter’s narrow rings as well as its two moons. In this detailed James Webb image of Jupiter, the moon Almatia is a bright dot on the left and the moon Adrastia is at the edge of the rings between Almatia and Jupiter. The second image is a close-up view of the planet Jupiter. In this image, three filters are used to capture the details of the planet’s stormy atmosphere, especially the auroras. You might be wondering why the colors in these images are not the same as what we see in other customer images. In these images, the James Webb telescope recorded light in the infrared spectrum, not the visible light spectrum; Therefore, the colors of the two images are not the same as the colors of the unaided eye. The infrared data was mapped onto the visible light spectrum so these images are “false color” rather than “true color”.

A composite image of Jupiter captured by the James Webb Space Telescope’s NIRCam camera; The orange glow around the poles are auroras.

Future missions to the client

JUICE ( Jupiter’s Icy Moons Probe): Jupiter’s Icy Moons Probe (JUICE) is a European Space Agency mission selected as part of the Cosmic Vision science program. The probe is expected to launch in 2022 and reach Jupiter in the 2030s after visits to the inner solar system. This probe is dedicated to studying the icy Galilean moons: Ganymede, Callisto, and Europa. All three moons have subsurface oceans, which increases their potential for discovering life.

Europa Clipper: NASA’s Europa Clipper probe is dedicated to the study of Europa, Jupiter’s icy moon, and will investigate the conditions of life beneath the icy crust of this moon. This probe will be placed in Jupiter’s orbit for close observation of Europa. The Europaclipper probe will be launched in the early 2020s and will reach Jupiter after a 6.5-year journey.

Chinese and Russian missions: China will also launch its first probe to Jupiter in 2029. This probe will reach Jupiter in 2036. Also, Russia is looking to send a probe to Jupiter that will be launched in 2030. This mission will last 50 months and will initially visit the Moon and Venus. Then he examines Jupiter and its moons.

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