Global satellite navigation system constellation

Everyone is familiar with the Big Dipper. Are they in the same constellation?

With the last Beidou navigation satellite successfully flying into space, China's Beidou global satellite navigation system has fully completed the constellation deployment. The name of the Beidou satellite navigation system comes from the famous symbol of the northern sky-the Big Dipper. These seven bright stars are arranged in a spoon shape around Polaris, which can help us to identify the direction at night, which is why China's global satellite navigation system is named after it.

So, why can the Big Dipper indicate the northern sky? What do they have to do with Polaris? How far is the Big Dipper from the earth? Are they in the Milky Way? How big is the Big Dipper?

There are many stars in the sky. Almost all the stars we can see with the naked eye are stars, including the Big Dipper, which can produce light and heat through nuclear fusion like the sun. Because the stars, including the Big Dipper, are outside the solar system and far away from the earth, we can't feel their heat or see their true size.

The earth revolves around the sun at a speed of 30 km/s, and the sun revolves around the center of the Milky Way galaxy with the earth and other celestial bodies in the solar system at a speed of 220 km/s. Although the earth has been moving in space, those stars are far away from us, and the distance caused by the earth's movement is very small, so the relative position of the stars in the night sky seems to be basically unchanged.

The position of the Big Dipper in space is just near the north celestial pole, and the Polaris is very close to the north celestial pole. Therefore, no matter how the earth revolves around the sun, the northern end of the earth's axis always points to the sky where the Big Dipper and Polaris are located, so these stars can indicate the north.

Just like the Big Dipper, Polaris is a star and a three-body system, and the other two companion stars are invisible to the naked eye. There is no direct relationship between the Big Dipper and the North Star, but their directions are roughly the same, and the actual distance is very far. For example, the distance between Shutian and Polaris in the Big Dipper is 545 light years.

Similarly, there is no direct relationship between the Big Dipper, and they all belong to their own star system. These stars are all about 100 light-years away from the earth, and they are all stars in the Milky Way. In fact, none of the stars visible to the naked eye are outside the Milky Way, and most of them are no more than 1000 light years away from the Earth. The following is a brief introduction of the Big Dipper:

η in Ursa major or η in Pojun is 0/04 light-years away from the Earth/kloc-,and its mass, radius and luminosity are 6. 1 times, 3.4 times and 594 times that of the Sun, respectively. Eta Ursa major is a very young star, and its age is only100000 years.

Kaiyang, or Wuqu Kaiyang, is 83 light years away from the earth, and its mass, radius and luminosity are 2.2 times, 2.4 times and 33 times that of the sun respectively. There is a companion star visible to the naked eye next to Kaiyang, which can be seen by anyone with good eyesight. Through the analysis of astronomical telescope, Kaiyang actually belongs to a system containing six stars.

Yuheng, or Lian Zhen Yuheng, is 83 light years away from the earth, and its mass, radius and luminosity are 2.9 times, 4. 1 times and 102 times that of the sun, respectively. Yuheng belongs to a binary star system, and its companion is a brown dwarf star.

Tianquan or Wen Qu