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It has always been common knowledge that the Sun is a star, and that the Earth and the other planets of the solar system move around it. But in fact, the Sun is not really a "star", and while other planets revolve around the Sun, the Sun will also revolve around the Milky Way with other planets.
The Sun orbits the Milky Way at a rate of 220 km/s, which is 6.4 billion kilometers in a year. The Sun travels such a long distance each year, why doesn't the position of the stars we observe on Earth change?
The Solar System and the Milky Way
There are hundreds of billions of galaxies in the universe, and the Milky Way, where the Sun is located, is just one of them. The Milky Way is a flattened spiral galaxy about 120,000 light-years in diameter and about 200 billion sun-like stars in its interior.
There is a supermassive black hole at the center of the Milky Way, which attracts celestial bodies on the four spiral arms around it. Our solar system is on the Orion Arm, one of the four spiral arms.
The Sun is about 260 million light-years away from the "Silver Heart", and its orbital speed around the "Silver Heart" is about 220 km/s, and it travels 6.4 billion kilometers per year. The orbit of the solar system around the "galactic center" is called a "galactic year", and a "galactic year" is equivalent to about 2.2-250 million Earth years.
Since its birth, the sun has been around the "silver heart" for 5 billion years and has made about 20 revolutions. As the Sun rotates, the planets in the system also revolve around the "Silver Heart" with the Sun. In this way, the trajectory of the planets is not a circle, but a spiral.
In the Milky Way, most of the celestial bodies are located in the region formed by the plane called the "galactic plane". When the sun rotates, it is not always in the galactic plane, but travels regularly in waves up and down the galactic plane.
About every 32 million years, the Sun crosses the galactic plane, and the last time the Sun crossed the galactic plane was 3 million years ago. Some scientists believe that when the sun passes through different regions in the Milky Way, it will have a certain impact on the earth.
In some areas, the density of interstellar matter is larger, and various small celestial bodies in the solar system, such as asteroids and comets, will be disturbed by the gravitational attraction of interstellar matter when passing through such regions, increasing the probability of the earth being hit by asteroids, forming a periodic "mass extinction". However, this is only speculation, and there is no definite conclusion.
In the universe, the sun revolves around the "silver heart" all the time, and after the earth orbits the sun for a week, it is no longer the original position of the universe. If that's the case, why hasn't the position of the stars changed so much?
A relatively stationary star
There is no absolutely stationary celestial body in the universe, all celestial bodies are in constant motion, and only in a specific frame of reference will they exhibit a state of rest. The same is true of the stars observed by humans, whether they are the sun, the earth, or other planets, which are in constant motion.
The reason why humans cannot observe the movement of various stars is that these stars and the earth are in a relatively static state. On Earth, all the stars that can be observed by the human eye are within 1,000 light-years of the Earth, including stars in the solar system and many exoplanets.
Humans on Earth can observe the five planets Venus, Jupiter, Mercury, Mars and Saturn with the naked eye. These five planets are driven by the sun and rotate around the "silver center" synchronously with the earth, and humans naturally cannot observe the changes in their positions.
Other stars outside the solar system are also revolving around the "galactic center", and they are almost at a relative standstill with the solar system. It's like two people riding in a car, and the two people in the car are in a relatively static state, and they can't feel each other's movement.
The solar system and other extraterrestrial bodies in the spiral arms of the Milky Way rotate around the "galactic center" together, forming a relative rest, which may have a slight difference in the speed of the movement of different stars, but their position changes cannot be observed by the human eye.
The distance between the Earth and the stars
Another factor that humans cannot observe changes in the position of stars is distance. The exoterrass that humans can observe is too far away for Earth.
Of the Big Dipper that humans can observe, the closest to Earth is the "star", which is 78.2 light-years away. Polaris, which is used to guide the way, is 433 light-years away from Earth. The closest star to Earth is Proxima Centauri, which is about 4.2 light-years away.
At such a distance, it is difficult for humans to visually observe their position changes. Suppose in an open area and a person is moving in front of you at a speed of 5 m/s, you can easily feel the change in his position. But if he's 10 kilometres away from you, it's hard to feel the change in his position.
The same is true for the stars in the Milky Way, which are in constant motion. However, due to the distance from the Earth and the fact that the universe is so open that there is no suitable reference, it is difficult to observe the changes in their position with the naked eye. Only with high-precision telescopes can subtle changes in their position be observed.
The scale of change of the stars is measured in tens of thousands of years, and now humans observe that the arrangement of the Big Dipper is like a "spoon", but before 100,000 it was more like a "shovel", and after 100,000 years, it will take on the shape of a "cart". The same is true for changes in other constellations, which often change in tens of thousands of years, and it is difficult to feel their changes in the short lifespan of human beings.
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The solar system and other stars in the Milky Way will revolve around the "silver center", and the earth and other stars will be in a relatively stationary state, even if the other stars have certain changes, but the degree of change is too small for the observing human beings to intuitively perceive their changes.
Compared to the universe as a whole, human beings are too small, too insignificant. But this does not prevent us human beings from exploring the universe, and it is precisely because the universe is so vast and vast that human exploration is more meaningful.
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