According to NASA, the Earth is on average 150 million kilometers from the Sun. However, the Earth’s orbit is not completely circular, but somewhat elliptical. That means the distance between the Earth and the Sun is 147.1 – 152.1 million km. However, on average, the distance between the Earth and the Sun continues to increase over time. The two main causes are the loss of mass from the Sun and the same forces that cause tides on Earth.

The fusion reactions that power the Sun convert mass into energy. As the Sun continuously produces energy, it gradually loses mass. Over the rest of the Sun’s life — about 5 billion years — the star is predicted to lose 0.1% of its total mass, said Brian DeGiorgio, an astronomer at the University of California, Santa Cruz. Live Science On 7/8.

According to DiGiorgio, 0.1% doesn’t sound like much, but it’s actually a very large mass, about the same as Jupiter. Jupiter has 318 times the mass of Earth. The gravitational force of an object is proportional to its mass. As the Sun’s mass decreases, the gravitational force on the Earth also weakens, causing the Earth to drift away by about 6 cm per year.

Just as the Moon’s gravity causes tides on Earth, Earth’s gravity also affects the Sun. This stretches the part of the Sun that faces Earth, leading to “tides,” says Britt Scharringhausen, associate professor of physics and astronomy at Beloit University.

The Sun rotates on its axis once every 27 days, faster than it takes Earth to complete one orbit around the Sun (about 365 days), so the tidal bulge is ahead of Earth. The gravity of this bulge pulls the Earth forward and pulls the Earth further away from the Sun. The same phenomenon causes the Moon to gradually move away from the Earth. However, these tidal forces have a very weak effect on the Earth’s orbit. They move Earth away from the Sun by only 0.0003 centimeters per year, DiGiorgio estimates.

“As the Earth moves away from the Sun, sunlight fades. Over the next 5 billion years, the Earth-Sun distance will increase by 0.2%, which is equal to the amount of solar energy reaching the Sun. The Earth’s surface will shrink by 0.4%. This is relatively small compared to the normal fluctuations in sunlight caused by the Earth’s elliptical orbit. So there is no need to worry. ” DiGiorgio said.

Over the next 5 billion years, the Sun’s brightness is predicted to increase by about 6% every billion years, which means that Earth’s temperature is gradually increasing and boiling the oceans. “This will make it impossible for humans to live on Earth before the Sun engulfs the Earth,” he said.

Specifically, in about 5 billion years, after running out of hydrogen fuel, the Sun will begin to swell and become a red giant. Scientists currently have some disagreements about how much the Sun is expanding. It’s unlikely that the Sun will grow large enough to reach Earth, but most estimates suggest that the star could swallow the blue planet.

“However, even if Earth existed, humans would not be able to live on it. The heat and radiation from the Sun would not only boil the oceans and atmosphere, but also boil the Earth itself,” DiGiorgio explained.

If we still want to live on Earth as the Sun expands, humans will have to gradually move the blue planet out, around Saturn’s orbit, to help Earth maintain a temperate climate suitable for life. “However, this is not entirely realistic. The simplest solution is to leave Earth and find another planet or star system,” DiGiorgio said.

Tu Tao (O Live Science)