The sun always emits constant amounts of charged particles into space. These particles are called the solar wind. The solar wind carries the solar magnetic field. Sometimes the local oscillations of the sun result in intense bursts of particles in a particular direction. If the Earth is in the path of the strong solar wind produced in these events, it is said to be facing a geomagnetic storm. The two most common causes of geomagnetic storms are coronal ejections (bursts of plasma from the Sun’s surface) and the solar wind, which escapes into space from low-density patches in the Sun’s upper atmosphere.

The speed of ejected plasma or solar wind when it reaches the Earth is an important measure. The higher the speed of the solar wind, the more intense the geomagnetic storm will be. Normally, the solar wind moves at exactly 1.4 million kilometers per hour; But extreme solar storms can be up to five times faster.

The most severe geomagnetic storm recorded due to coronal ejection occurred in September 1859. The particles hitting the ground caused electrical disturbances in the telegraph lines, which surprised the operators and in some more severe cases even caused telegraph machines to catch fire. According to research, if a geomagnetic storm with this intensity hits the earth today, it will cause nearly 2 trillion dollars in damages.

Earth’s magnetic field absorbs much of the solar wind like a shield

The emission of solar particles, including the solar wind, is extremely dangerous to any life unlucky enough to be in direct danger of it. However, the Earth’s magnetic field completely protects humans against this danger. The first thing a solar storm hits on its way to Earth is the magnetosphere. This region, which surrounds the Earth’s atmosphere, is filled with plasma made of electrons and ions and is dominated by the Earth’s strong magnetic field. When the solar wind hits the magnetosphere, it transfers mass, energy, and momentum to this layer.

The magnetosphere can absorb a large part of the daily energy of the solar wind; But the occurrence of solar storms may cause an energy spillover, transferring excess energy to the upper atmosphere near the poles. This rerouting of energy to the poles leads to dramatic aurora events, but it can also change the Earth’s upper atmosphere.

Different layers of the Earth’s atmosphere are affected by solar storms with different intensities.

Geomagnetic storms disrupt satellites in orbit in various ways. As the Earth’s atmosphere absorbs energy from magnetic storms, it warms and expands upward. This expansion dramatically reduces the density of the thermosphere. The thermosphere is a layer of the earth’s atmosphere that extends from 80 km to 1000 km above the earth’s surface. Higher density means more drag, which can be problematic for satellites.

This is the exact situation that led to the destruction of SpaceX’s Starlink satellites in February. Starlink satellites are launched into a low-altitude orbit, usually 100 and 200 km above the Earth’s surface, using a Falcon 9 rocket. The satellites then use their independent engines to overcome the drag force and lift them up to a final altitude of approximately 550 km.

The last batch of Starlink satellites in low Earth orbit faced a geomagnetic storm. Their engines could not overcome the strong drag force and eventually fell to the ground and burned up in the atmosphere. Drag force is just one of the threats space weather poses to space-based resources. A significant increase in energetic electrons in the magnetosphere during intense solar storms means that more electrons penetrate the spacecraft’s shield and accumulate in their electronic components. A flurry of electrons can discharge like small lightning strikes and damage electronic components.

Starlink satellites are placed in orbit in groups. 40 of these satellites were destroyed in early February this year due to a geomagnetic storm.

Penetration of rays or charged particles into the magnetosphere even during moderate geomagnetic storms can change the output signal of electronic devices. This phenomenon can lead to errors in any part of the spacecraft’s electronic system, and if this error occurs in one of the important parts, the entire satellite will be disrupted. Small errors are common and repairable, and complete errors are rare and irreparable.

These changes can make it difficult to lock onto GPS signals and result in errors of, for example, a few meters. For many industries such as aviation, maritime, robotics, transportation, agriculture, military industries, and many others industries, a GPS positioning error of several meters is not acceptable at all. Automatic guidance systems also require accurate positioning.

The solar wind consists of charged particles that bombard the Earth’s magnetosphere.

The solar wind blows in the solar system far beyond the orbit of Pluto and forms a large bubble called the heliosphere. According to the European Space Agency, the heliosphere is in the form of an elongated balloon that moves with the Sun and its closest boundary is approximately one hundred astronomical units (AU) from the Sun. An astronomical unit is the average distance from the Earth to the Sun, or roughly equivalent to 150 million kilometers.

The heliosphere acts as a protective shield and protects us from cosmic rays consisting of energetic particles that can damage living cells. Cosmic rays originate outside our solar system and travel through space at nearly the speed of light. Without the protective bubble, these energetic particles would bombard the Earth continuously. “Without the heliosphere, life would certainly have evolved differently, or perhaps not at all,” says Richard Marsden, a heliophysicist at the European Space Agency.

This GIF image visually shows computer-processed data from the solar wind.

Although the solar wind flows continuously from the Sun, its properties such as density and speed vary during the 11-year cycle of the Sun’s activity. During this cycle, the number of sunspots and the level of radiation and ejected material fluctuates from the solar maximum to the solar minimum. These changes affect the characteristics of the solar wind, including the strength of the magnetic field, its speed, temperature, and density.

According to the website spaceweatherlive.com, which predicts space weather, the average speed of the solar wind is approximately 300 kilometers per second (1.1 million kilometers per hour). In comparison, a Category 5 hurricane can hit its surroundings at a speed of 241 km/h.

During Mariner 2’s flyby of Venus, the spacecraft not only discovered the solar wind; He also identified two distinct streams of the solar wind, one fast and the other slow. The speed of the slow current was reported to be nearly 349 kilometers per second; While the fast current moves at twice this speed.

The origin of the fast flow of the solar wind was identified in 1973 using X-ray images of the Sun’s corona from the Skylab space station. Coronal cavities, or cooler regions of the Sun with open magnetic field line structures that allow the solar wind to propagate relatively easily, are responsible for the formation of fast solar winds.

Anomalously fast solar winds can be generated during mass ejection events from the Sun’s corona. During these events, the wind speed can reach more than a thousand kilometers per second. Despite the staggering speeds that the fast streams of the solar wind can reach, it’s the slower solar winds that have baffled scientists. “The slow solar wind is in many ways a bigger mystery,” says Jim Klimczak, a solar physicist at NASA’s Goddard Space Flight Center in Maryland.

Mass ejection from the Sun’s corona as seen by the Solar and Heliospheric Observatory (SOHO).

NASA’s Ulysses spacecraft, launched in 1990, revealed some clues about the origin of the slow flow of the solar wind as it flew around the Sun’s poles. The spacecraft found that during periods of minimum solar activity, the solar wind originates mainly from the solar equator.

According to NASA, as the solar cycle progresses towards maximum activity, the structure of the solar wind changes from two distinct regimes (fast at the poles and slow at the equator) to a mixed and heterogeneous flow. NASA’s Parker Solar Probe will investigate this mystery of the Sun during its seven-year mission. Klimchak sees Parker as promising to provide new fundamental knowledge about this.

The effects of our wind star are felt throughout the solar system. “My feeling is that if the Sun sneezes, the Earth will get cold,” says Nicky Fox, director of the Heliophysics Unit at NASA Headquarters. “Because we always feel the impact of what happens on the Sun, thanks to the solar wind.”

On Earth, the solar wind is responsible for the formation of dazzling auroras around the polar regions. In the Northern Hemisphere, this phenomenon is called the Northern Lights, and in the Southern Hemisphere, it is called the Southern Lights. If the speed of the solar wind is high enough, geomagnetic storms may form. These storms can extend the auroras closer to the equator compared to calmer space weather conditions.

Mass ejection events from the Sun’s corona can create geomagnetic storms that lead to stunning auroras like this one in Alaska.

Geomagnetic storms can also knock out satellites and power grids and threaten astronauts. During these storms, astronauts on the International Space Station must seek shelter, and until the radiation storm has passed, all spacewalks are suspended, and sensitive satellites are turned off.

SpaceX has already seen the damage that space weather can cause; Just as a geomagnetic storm destroyed 40 Starlink satellites worth more than $50 million in February 2022. During release into very low orbits (between 100 and 200 km), Starlink satellites turn on their engines to overcome the drag force and raise themselves to a final altitude of approximately 550 km.

During a geomagnetic storm, the Earth’s atmosphere absorbs the energy of the storms and heats up and expands upwards; An event that leads to a significant densification of the thermosphere. The thermosphere is the fourth layer of the earth’s atmosphere, which extends from approximately 80 kilometers to about a thousand kilometers above the earth’s surface.

A denser thermosphere means more drag, which can be problematic for satellites. In February 2022, a batch of Starlink satellites that had just been released into orbit failed to overcome the greatly increased drag caused by a geomagnetic storm; As a result, they started to fall towards the ground and finally burned up in the atmosphere.

Solar weather can have very expensive consequences; Therefore, it is important to increase our understanding and monitoring, and prediction of such events. Solar wind scientists are working to learn more about space weather and improve predictions. “We cannot ignore space weather,” says NASA. But we can take appropriate measures to protect ourselves.”

The Heliophysics System observatory consists of a fleet of spacecraft designed to study our dynamic solar system.

Heliophysics missions study the Sun and its effects on the Solar System, including the effects of the solar wind. According to NASA, the purpose of these missions is to understand everything; From how planetary atmospheres are formed and how space weather affects astronauts and near-Earth technologies to understanding the physics governing our cosmic neighborhood in space.

Understanding the solar environment is not a simple achievement; For this reason, a whole fleet of spacecraft is working with the aim of understanding the Sun and its behavior. These missions can be considered as a single observatory called the Heliophysics System Observatory (HSO).

The heliophysics system observatory consists of several solar, heliospheric, geospace, and planetary spacecraft; including the Parker Solar Probe with the audacious goal of touching the Sun, the Solar and Heliospheric Observatory (SOHO) which is a joint mission of NASA and the European Space Agency, the Solar Earth Relations Observatory (STEREO) which consists of two almost identical observatories, and the European Space Agency’s Solar Orbiter which For the first time, it explores the unknown polar regions of the sun.