The earth has been moving, why is the position of the stars in the sky basically unchanged?
There are countless stars in the sky. Every star is moving. It is impossible to not move. The solar system is moving and the earth beneath it is also moving. You may not know that the earth revolves around the sun at a speed of 30 kilometers per second.And we think that the stars do not change from ancient times. This is an illusion. In fact, according to the star positions recorded in ancient books, such as the Big Dipper, Orion, Ursa, etc., the positions have changed in the past thousands of years.What's more, tens of millions of years, hundreds of millions of years. To measure the universe in the short life of human beings, it must be immutable, but it is not.
Standing in the open space, if one person is 500 meters away from you, the other person is 50 meters away from you, the person who is close to you moves a short distance, you can find that person who is far away from youYou need a greater range of movement before you can detect it. Those stars that are far away from the earth are also moving, but they are too far away, so it seems that they have not changed for a long time..
For example, Barnard Star, 6 light years away from Earth, 6 light years is relatively close in the universe. It is a red dwarf, because it is closer to us, and at this stage,It has been moving towards the sun, and its position has changed greatly in less than 20 years, as shown in the figure.
On the earth, nearly 7,000 stars can be seen with the naked eye, about nine-tenths of which are less than 1100 light-years away from the earth, and most of them are within the range of 500 light-years.Every time, the position of the stars will change a little bit, but judging from the short life of human beings, there seems to be no change. If you pull the time scale to more than 1000 years, you can see that the position of the stars has changed.
Those thousands of light years away from Earth, not even in the Milky Way, will not change for a long time. And those nebulae far away millions, tens of millions, or even hundreds of millions of light years away., Galaxies, in our night sky can not change for thousands of years, the reason is because it is too far away.
The universe is constantly moving, and the Big Dipper will change significantly after 100,000 years. The starry sky is different on every clear night.
Art / Science Dock
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