Can you still see stars on Earth after one trillion years?

2019-12-27 | Old porridge science original |

I guess you must be thinking that the universe is expanding and the stars are far away, so after one trillion years, the stars will be far away, and even one will be invisible.

Actually you think too much.

  • First of all, the earth will probably not last that long.

The reason that the earth can breed life, including you and me, is because it is not too far from the sun and not too close. The distance between the earth and the sun is about 150 million kilometers. Scientists call this distance "1Astronomical units ". In fact, this distance is not fixed. The orbit of the earth around the sun is an elliptical orbit close to a circle, sometimes farther and sometimes closer. As the sun consumes its energy a little bit, the sunAccording to the law of universal gravitation, the sun becomes lighter, its gravitational force on the earth will become smaller, the earth will move away from the sun a little bit, and may eventually run near the orbit of Mars. Of course you do n’t have to worry about MarsHit the Earth, because Mars will go further.

But there is a more terrible problem. The sun will become larger and brighter. About 5 billion years later, the sun will grow to engulf Mars orbit, and the earth will run in the sun by then.

You who love astronomy must know that the sun at that time was a red giant star, and its volume will be 100 million times larger than it is now. At the same time, its hot atmosphere will burn everything on the earth. Another 12In 100 million years, all the hydrogen in the sun's core has been burned into helium. At that time, "helium flash" will occur, and a strong explosion may explode the earth into fragments, and the earth does not exist!

Let's make a summary: after 5 billion years, the earth will be engulfed by the sun; soon after, the earth will be blown up by the sun into fragments. The earth has disappeared, so naturally you cannot see the stars on the earth.

  • Secondly, there may be more and more stars instead of fewer and fewer.

The solar system is a member of the Milky Way, a very small one. We stood on the earth and looked up at the stars. Except for a few planets in the solar system, we saw more than 6,000 stars yes,Only so much can be seen with the naked eye. Most of them are only stars in the Milky Way, and only those stars closest to the solar system. Farther away, you can't see them with the naked eye, so you think there is black.

There is a galaxy called Andromeda near the Milky Way. It is much larger than the Milky Way. What is more frightening is that it is flying towards the Milky Way or it may be that we are flying past. In short, the two galaxies are approaching at high speed. About 20After billions of years, these two neighbors will collide.

Does the collision of galaxies explode? It is not likely, because the distances between the stars in the Milky Way are very, very similar to Andromeda, so when the two galaxies meet, most of them pass by, even if there areStar collisions are also small-probability events.

There will be more and more stars in the sky, and the night sky will become brighter. After about 4 billion years, you look up at the sky again. A brand new galaxy will reflect the night sky brightly. Of course, the sun has already turnedThe earth is burnt.

  • So, is the theory of the Big Bang and the inflation of the universe wrong?

Many astrophysicists now think that distant galaxies are moving away and away from us at the speed of light. It seems difficult to understand, but scientists insist that the speed of expansion of space can exceed the speed of light. ThisThis means that after several billion years say one trillion years, those galaxies farther away from us are completely invisible.

The expansion of the universe does not mean that the galaxy itself is also expanding. Within the galaxy, the role of universal gravity is greater, so the galaxy-fairy galaxy will not disperse, and the stars are still circulating in the clusters.

At that time, if you were lucky enough to stand here and look up at the sky, you would only see more starlight.

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