On a clear, moonless summer night, there is a majestic, faintly glowing band of light in the sky that spans the star-studded sky and looks like a large river flowing through the sky, called the Milky Way. "The Milky Way drifts back to the stars at night, and the flowing clouds in Yinpu learn the sound of water." In ancient my country, the Milky Way was regarded as the Milky Way for a long time, and there was a beautiful legend that "the Cowherd and the Weaver Girl met on the Magpie Bridge on the Milky Way every year on the seventh day of the seventh lunar month." In fact, Altair is 15.7 light years away from the earth, Vega is 27 light years away, and Altair and Vega are 14 light years apart. If we set out from two places, even if we take the fastest modern rocket, we will not be able to meet each other after hundreds of years.
The Milky Way is densely packed with distant stars, forming a huge star system called the Milky Way. The Milky Way has more than 100 billion stars and a large number of nebulae, and our sun is one of them. But if you observe the Milky Way from a distant place, you will see that the entire Milky Way is thick in the middle and thin around the edges, similar to a discus. The diameter of the Milky Way is approximately 100,000 light-years, and its thickness is approximately 10,000 light-years. The sun is about 33,000 light-years away from the center of the Milky Way. The stars in the Milky Way are constantly rotating around the Milky Way. It takes about 200 million years for the Sun to make one revolution in the Milky Way. It can be seen that the solar system is not very big and is only a drop in the ocean compared with the Milky Way. As for the earth, let alone that. The Milky Way lies diagonally in the sky, so as the Earth rotates and revolves, the Milky Way changes its position in the sky from time to time in our sight, forming a beautiful Milky Way picture. On summer nights, the Milky Way faces north and south; on winter nights, the Milky Way faces east and west.
The central axis of the Milky Way is constantly rotating, and each rotation takes about 250 million years. In addition, it moves through the universe at a speed of 214 kilometers per second.