Even if Heliocentrism later overthrew the old saying, people just changed the center of the earth to the sun. With the development of science and technology, we gradually realize that the sun and the earth are just ordinary planets in the universe. The position of the sun and the earth is not always the same, they are always in motion.
The stars in the night sky are actually other stars in the universe. Since the sun is moving, so are they. The question is, why haven't the positions of these stars changed in the Milky Way? Has the constellation been like this for thousands of years?
In the past, people thought that the sun was just a planet revolving around the earth. At that time, scientists thought that there were only three celestial bodies in the universe, the sun, the moon and the stars. Later, other planets such as Mercury and Venus were distinguished, but people still think that they revolve around the central celestial body-the Earth.
In fact, people's cognition was limited at that time, and this theory was also in line with the consistent characteristics of human beings. After human beings reach the top of the food chain, they no longer look at nature, so the church takes geocentric theory as the mainstream thought for the convenience of management.
At that time, the poorest and most miserable people could be proud of being the center of mankind and the universe, and the church could cover up many contradictions. This is why Copernicus' Heliocentrism was so strongly opposed, because it was hated not only by the church, but also by many self-righteous ordinary people who were immersed in it.
After many scientists paid the price of their lives, Heliocentrism finally replaced the geocentric theory. But Heliocentrism is not perfect. Copernicus established a complete concept of the solar system, but did not establish a correct concept of the universe. The sun is not the center of the universe. However, this time, mankind has not made the mistake of being willful and complacent again. With the development of science and technology, human beings gradually realize that there is a larger scope in the universe than in the solar system. With the help of astronomical telescope, we discovered the Milky Way.
The solar system and other star systems are distributed in the Milky Way. At this moment, the sun incarnates as a "planet" and revolves around the center of the Milky Way. Moreover, astronomers found that the position of the sun is not in the center of the Milky Way, but on a spiral arm of the Milky Way, which is about 20,000 light years old. And our so-called stars are other stars in the same galaxy.
Since the sun revolves around the center of the Milky Way, it will also have the period and speed of revolution. Indeed, according to astronomers' calculations, the period of revolution of the sun is about 270 million years, and its revolution speed is 220 kilometers per second.
This speed exceeds all the known celestial bodies in the solar system, which means that the sun can run about 7 billion kilometers a year, and the moving distance of other stars is not too much.
The Milky Way is a more advanced system than the solar system, and the galactic coefficient in the universe is endless. We often say that the Milky Way refers to this one where our solar system is located, and other galaxies are called extragalactic systems. It has five spiral arms, and the solar system is on Orion's spiral arms.
Planets revolve around stars because they are attracted by them, so what does a star revolve around the Milky Way? Of course, that's gravity, but about what's in the center of a galaxy, it is generally said that there is a silver-core black hole in the center of a galaxy. Because the growth direction of the Milky Way is from the inside out, the closer you get to the center, the older you get.
For example, our solar system is only about 4.6 billion years old, and the age of the Milky Way is about 65.438+0 billion years old. Therefore, both the distance from the center and the position of the spiral arm of the sun are immature. But in the center of the galaxy, the situation is completely different.
There are many white dwarfs in the center of the Milky Way. They are the tombstones of the stars, telling that there were stars here. Because the life of a star is limited, it will collapse after running out of energy, leaving a core at last, and stars with a mass below 8 suns will eventually become white dwarfs. But those stars with huge mass, far more than eight times that of the sun, are not white dwarfs after fading, but two other celestial bodies with super huge mass and density. When a massive star dies, it leaves a neutron star or a black hole.
Both of them have great gravity, and when light escapes from neutron stars, it will appear curvature, that is, the original straight-line propagation path will become curved propagation. A black hole absorbs light directly, and no one can escape!
Therefore, astronomers predict that there is at least one galactic black hole at the center of our galaxy. Under its great gravity, the sun and stars revolve around it. Since everyone is running wildly, why are the positions of these stars almost unchanged from the earth? For example, Polaris is always above the North Pole of the Earth.
There are two reasons, one is relative static, and the other is that the distance is too far, and it takes a long time to completely observe the movement.
There is no stillness in the universe, everything is moving, so the position of the stars above us is actually changing. We can't see it because we are in the same system.
Standing on the equator of the earth, a person moves 40 thousand kilometers a day, but he is completely unaware of it. This is because we belong to a part of the earth, and we are in a moving system with all the objects on the earth, and we are in a relatively static state, so we can't perceive that the earth is rotating.
Send a satellite into space and hover over the earth instead of around it, so that you can see the rotation of the earth. Because at this time, the satellite has separated from the earth, and it no longer belongs to a part of the earth. From the perspective of a third party, the earth is moving.
Similarly, our solar system and other star systems are part of the Milky Way. Imagine the Milky Way as a train, the sun is a carriage, we are passengers in the carriage, and other star systems are other carriages of the same train. Although we need great efforts to walk from one carriage to another, it is undeniable that each carriage is relatively static.
So we are moving with other stars, everyone is moving in a system, and the position is relatively unchanged.
However, there is a problem with this explanation. Even though it can be regarded as relatively static in rotating around the Milky Way, don't forget that the universe is really expanding, just like two ants in a balloon. After the balloon expands, they can see each other getting farther and farther away. Why don't people feel that these stars are getting smaller at all? I'm afraid there is still a long way to go.
In the Milky Way, the distance between stars is measured in light years. For example, the nearest star is proxima centauri, and the distance between them is about 4.3 light years, while some distant stars may be hundreds, thousands or even tens of thousands of light years.
In other words, some starlight we see is actually the light emitted by this star hundreds of thousands or tens of thousands of years ago. Its position has changed, but the light after the position change has not yet reached the earth. The light we see comes from its previous position.
The position of the constant star that we think is actually a long time ago, which is equivalent to the fact that aliens 2200 light years away have now seen Qin Shihuang enthroned, and Qin Shihuang has already died on the earth. According to this law, astronomers used models to simulate the shape of the Big Dipper 654.38 million years ago. Surprisingly, they found that the Polaris 654.38 million years ago was not like a spoon today, but more like an arrow. Then according to this speed, it is predicted that the Big Dipper will become another shape in 654.38+ million years.
Another example is the shield of Orion, which was formed only a thousand years ago. It is quite possible that we are different from the Orion seen by the ancient Egyptians. After tens of thousands of years, this shield will disappear, and it may become a puppy in the hands of Orion.
In fact, this astrology, like the landform on our earth, is always temporary. Change is invisible on the earth, because the speed of change is very slow and the time is very long; The invisible change in the universe is not its slow speed, on the contrary, the speed of matter in the universe is very fast, and we can't see it because it is too far away. What we observe is always one step slower than the celestial body itself. A star 65,438+0,000 light years away has also moved a distance of 7 billion kilometers, and it will take us 65,438+0,000 years to know the Tao. By this time, the observer has changed thousands of stubble.
So it's not that we can't see the position changes of these stars, but that this change has lasted for too long. If you want to see the change of location, you need to wait patiently for hundreds, thousands, tens of thousands or even hundreds of thousands of years.
Then some people will object that we don't look at the stars hundreds or thousands of light-years away, but only those that are closer to the solar system.
Let's assume that the moving speed of proxima centauri, like the sun, is 7 billion kilometers a year, which is a great distance for human beings, but a very small distance in the universe. 7 billion kilometers is converted into a cosmic unit, which is about 0.0007 light years. In a galaxy with a diameter of10.20 million light years, there is almost no movement.
Then the change of the distance between the sun and proxima centauri is nothing in the Milky Way. As a human with "jet lag", it is almost imperceptible. If there is an obvious position change between proxima centauri and the sun, human beings need to wait for a long time, so the present life span of human beings is invisible.
If you count the ancient astrology, the time for humans to observe the universe is about 5000 years, which is not enough for the universe to observe the obvious changes in astrology. So the star chart drawn by the ancients can still be used today. The ancients used the Big Dipper to guide the way, and we can still continue this tradition now.
Like our map, the star map is "eternal" for human beings, but for celestial bodies in the universe, this is their moment.
The distribution of the earth's land and sea has experienced separation and integration, and will continue in the future. In the past billions of years, the positions of the stars in the Milky Way galaxy have been near and far, and the stars have declined one after another and been born one after another. Compared with their cycle, human life is too short, even less than their moment.
In this way, the original geocentric theory of human beings is very funny. Carbon-based life on a planet thinks that it is the center of the universe, which now seems to be the embodiment of ignorance.
This also shows how much scientists such as Galileo and Copernicus have contributed to mankind. Without them, human beings will never realize their smallness. Ignorance will bring arrogance, which is the biggest obstacle to human progress.