The Sun will gradually become brutally brighter, hotter, and larger over time. Billions of years ago, the Sun was 20 percent dimmer than it is today when a series of molecules danced together to form living things. At that time, even the dinosaurs faced a fainter and smaller star.

Today, the sun is halfway through its hydrogen life and is still 4 billion years away from entering the death phase. However, in the next few hundred million years, the temperature and brightness that is giving life to our planet today will lead to its destruction. A few hundred million years is like a blink of an eye on a cosmic scale.

The sun sows the seeds of its destruction based on its fundamental physical properties. In the current conditions, our star consumes 600 million tons of hydrogen every second; So the atoms collide with each other in a nuclear inferno with a temperature of more than 15 million degrees Celsius. Of these 600 million tons, 4 million tons of hydrogen are converted into energy, which is enough to light up the entire solar system.

The fusion reaction is not completely clean and the resulting product is helium. Helium has nowhere to go because the deep convective cycles that continuously churn up the material inside the Sun do not reach the core, where helium is formed; Therefore, helium remains there in an unused, motionless, and stagnant form.

The Sun is in constant equilibrium on the edge of a nuclear knife. On the one hand, energy is released from the fusion process, which, if left unchecked, can cause the sun to explode or at least expand. In front of this force, there is the gravitational weight of the sun, which exerts an inward force. If this force is released, the sun’s gravity will cause it to collapse and turn it into a black hole the size of an average city.

So what happens when an unstoppable force meets an irresistible force? A pleasant balance is established and the sun can continue to exist for billions of years. If for any reason the temperature of the inner nuclear inferno increases randomly, other parts of the star will also heat up and its outer layers will swell. In this way, the gravitational pressure decreases and the nuclear reactions slow down. If the Sun randomly contracts, more material will force itself into the core, where it will participate in the nuclear dance. The energy released as a result of this event causes the star to re-inflate to normal proportions.

On the other hand, helium, which is a nuclear product, replaces hydrogen and disturbs the balance. In this state, the sun has no choice but to pull internally, because gravity is unyielding. Meanwhile, nuclear reactions intensify and increase the temperature, which eventually causes the sun’s surface to glow and expand.

Slowly, as helium continues to accumulate in the core of the Sun, or any star of similar mass, the Sun grows larger and brighter in response to this process. It is difficult to predict exactly when this glow will become catastrophic for the Earth, this issue is strongly related to the relationship between the rays, the atmosphere, and the ocean; But the general estimate is that we have about 500 million years before life on Earth becomes impossible.

The burning sun will increase the temperature of the earth’s surface. It evaporates at higher ocean temperatures. Since water vapor is an important greenhouse gas, a large part of it remaining in the Earth’s atmosphere leads to higher surface temperatures. Higher temperatures lead to more evaporation of the oceans, setting the stage for the greenhouse cycle. Finally, we will witness the escape of a large part of the earth’s waters into the atmosphere.

Without water to lubricate tectonic activity, tectonic plates stop moving. Without tectonic activity to pull carbon out of Earth’s atmosphere, the planet’s air density would increase dramatically. As a result, in a few hundred million years, we will become Venus, the twin planet of Earth, which experienced the same fate billions of years ago; Two dead worlds in the hands of their parent star.

The habitable zone is the region around a star where the temperature is suitable for the flow of liquid water on the surface of a planet. Temperatures near the star are too high to prevent any atmospheric complexity so that water exists only as vapor. Outside this range, the temperature is very low.

Earth is now roughly in the middle of the Sun’s life belt, Venus is on the inner edge, and Mars is almost outside. As the age of the sun increases and its brightness increases, the life belt will reach more distant parts of the solar system; So if we want the Earth to survive this process, we have to move it.

Moving a planet will not be an easy task; But fortunately, we are dealing with vast astronomical time scales and we don’t need to move the earth today. In fact, we have hundreds of millions of years to plan this transition. To do this, we can use the same stabilizing force that keeps the planets in orbit around the sun, and that force is nothing but gravity.

The first thing we need to do is find an energy source. Raising the earth’s orbit requires a lot of energy, and this energy has to be supplied from somewhere. Fortunately, we can use the planet Jupiter. Since this gaseous world is 318 times heavier than Earth, its simple movement through the sky provides a surprising amount of kinetic energy, and a small amount can be borrowed.

Instead, you can reach into your pocket and pull out a bouncing meatball. Suppose, this ball is durable and indestructible. You throw the ball at the train. The ball hits the train and bounces back. Then you grab it and move forward a bit. With just a little practice, and through simple conservation of momentum, you’ll find that you can steal some of the train’s energy and give it to yourself and the rolling platform. The train barely notices these collisions, but you do. If you get enough power you can move on without facing disaster.

Now let’s return to the example of Earth and Jupiter. The above analogy is suitable for preventing Jupiter from colliding with our planet, except we use asteroids instead of bouncing balls. We can send asteroids on long orbits around Jupiter. In this scenario, the gravitational interaction between the planet Jupiter and the asteroid leads to an increase in the speed of the asteroid and, in turn, a slight decrease in the speed of the giant Jupiter. Then we can bring the asteroid back to Earth, rotate it in the opposite direction, and achieve the desired force by slowing down its motion.

Running the above process once doesn’t have much effect; So we have to repeat it for hundreds of millions of years so that the Earth can reach higher orbits and thus escape from the wrath of the sun. If our descendants can control this process, they can move the Earth into a safe zone of the habitable zone.

If you are not interested in changing the arrangement of the planets, but have the ability for super-engineering projects, we have another solution for you. The main problem with the sun is that helium is a natural product of our star’s fusion process. The hydrogen fusion ratio is defined based on the total mass of the Sun; The bigger a star is, the faster it burns, and in the same way, smaller stars burn at a slower rate; Therefore, if we want to limit the amount of helium production, we must slow down the fusion reactions. The easiest way is to reduce the total mass of the Sun.

Fortunately, the sun is naturally decelerating, but not fast enough. The surface of the Sun continuously emits an endless stream of tiny charged particles, which we call the solar wind. In terms of human-scale statistics, the amount of mass that the Sun loses through the solar wind is 1 to 2 million tons per second, which is an incredibly high rate; But this speed should be increased a little.

One way to control the solar wind is to build a series of particle accelerator stations in orbit around the Sun’s equator. These stations continuously exchange charged particles and create a loop of current in the shape of the solar belt. This current loop creates a torus (donut-shaped) magnetic field that can transform the solar wind into polar outflows in the direction of the sun’s rotation axis and safely remove harmful particles from our planet.

The torus magnetic field can be used to compress the star. According to this method, first, the stations are turned off and thus the particles fall into the sun. Then, by turning on the stations, the magnetic field is interrupted and the falling process is reversed. The magnetic field surrounding the sun’s equator is compressed, forcing particles to be repelled from the sun’s poles.

If our descendants are advanced, they can capture the elusive solar wind and use it for other purposes, such as fusion reactor systems to power an entire facility, and if they are creative, they can direct the outflow of the solar wind in one direction and use it as a booster rocket. use solar to guide the solar system to new points in the Milky Way or even outside the galaxy.

Of course, the technique of moving the star reduces the brightness of the sun; Because despite the lower mass, the fusion reactions take place in a quieter atmosphere, which reduces the power and dimensions of our star. In this way, the life belt moves to an inner part. We may not realize this at first, because the things we do are in opposition to the natural tendency of the life belt to move outward; But eventually, after the Sun has lost 10-20% of its mass, we have to move the Earth to the inner part of the life belt to keep it in the right spot.

In the end, we are left with a smaller, long-lived star. The smallest red dwarfs with a mass of a little more than one-tenth of the Sun can live for trillions of years; But at the same time, it has a more chaotic nature, because due to their low mass, they are subject to stellar explosions that periodically double their brightness. If our descendants want to take this path to increase the life of the sun, they must definitely prevent these explosions.

All in all, if humanity can survive for billions of years, it will probably become an interplanetary or interstellar entity. In this situation, there will be no need to save the land. Perhaps our distant descendants can preserve the land from which they sprang as a mark of respect. Perhaps this is necessary because no other world is as suitable for life as Earth. Ultimately, perhaps, it is an art project, an opportunity to create beauty and wonder on an interplanetary scale, before the fires of nuclear fusion die out and our star breathes its last. The last chapter of the story ends the billions of years of life of the solar system.