What is the Big Dipper? Are they in the Milky Way?

In the night sky, only Andromeda, Triangle and Small Magellanic Cloud, four celestial bodies showing clouds and fog, are extragalactic galaxies visible to the naked eye, and other naked-eye stars are all within the Milky Way, most of which are no more than 65,438+0,000 light years away from the Earth (the radius of the Milky Way is 50,000 light years), including the famous Big Dipper. Among the 88 constellations in modern astronomy, the Big Dipper is a part of Ursa Major, and its distance from the Earth is about 100 light-years.

Of course, the Big Dipper is in the Milky Way, and all the stars we can see with the naked eye are in the Milky Way. Except for a few galaxies (clouds) outside the Milky Way, no stars can be seen with the naked eye (except supernova explosions).

The naked eye can see that there are more than 6,000 stars in the night sky, while the Milky Way has hundreds of billions of stars. Most of these stars are too far away from us, and some are too small, too dim and too close to our naked eyes.

The diameter of the Milky Way is 654.38+ million light years (now some new discoveries think it is 200,000 light years), while the farthest star visible to the naked eye is more than 654.38+ million light years, most of which are hundreds of light years. The darkest star visible to the naked eye is a 6-magnitude star.

The Big Dipper is the seven stars pulled together by human beings. They are not together and have nothing to do with each other. In ancient China, the seven stars that make up the Big Dipper were called Shu Tian, Tian Xuan, Celestial Pole, Tianquan, Yuheng, Kaiyang and Ursa Major.

These seven stars are between 78 light-years and 124 light-years, and their apparent magnitude is between 1.77 and 3.45.

The brightest star is the five-pointed star of Beidou, and its apparent magnitude is 1.77. The darkest star is the four-year star of Beidou, and its apparent magnitude is 3.45.

Apparent magnitude is calculated according to the brightness of starlight observed by human beings. The smaller the number, the brighter it is, and there are negative numbers.

Although the change of stars is relatively small, it will change with time. The position of the Big Dipper changed a little thousands of years ago, but it is difficult for human eyes to observe it. Modern scientific instruments can accurately measure it. Tens of thousands of years have passed and this change is obvious.

This is roughly the case with the Big Dipper.

Welcome to comment and discuss.