What's the difference between Ursa minor and Ursa major?

Ursa major is one of the brightest and most important constellations in the northern sky. The famous Big Dipper is in this constellation. The constellation Ursa major can be seen all year round, and the best observation time is after dusk in spring. The stars in Ursa major are imagined as the image of a big bear. On the map, the bucket handle of the Big Dipper is the long tail of the big bear, the four stars of the Big Dipper are the body of the big bear, and other darker stars constitute the head and feet of the big bear. In ancient Greek mythology, this big bear is the embodiment of a gentle and beautiful girl, Crystal. Legend has it that Callisto was loved by Zeus, the king of gods, and gave birth to his son Achatz. Zeus' wife Hera was very angry when she learned about it. She decided to punish Crystal with magic. Suddenly, Callisto's white arms turned into claws covered with black hair, and his red lips turned into a maw like a maw. The beautiful girl finally turned into a big bear. Later, Zeus knew about it, so he lifted the bear to the sky and became the constellation Ursa major. There are more than 100 visible stars in Ursa major, including 6 second-class stars, 6 third-class stars and many other fourth-class stars. The six second-class stars are all distributed on the Big Dipper, so the Big Dipper is particularly eye-catching in Ursa Major. After dusk in spring, this big bear hangs upside down in the northern night sky, and its tail (that is, the barrel handle) points to the east. Therefore, our people regard Ursa Major as a sign that indicates spring. Ursa major has a famous binary star, which was called Kaiyang Star and Auxiliary Star in ancient China. People often use them to check their eyesight. On a clear night, if the auxiliary star next to Kaiyang Star can be seen by naked eyes, it can reach 1.5 by visual inspection. Astronomers observed that the distance between Kaiyang star and auxiliary star is very close, but in fact they are far apart. There are many binary stars or multiple stars in the celestial sphere, which seem to be together, but in fact they are not related.

little bear

Draw a straight line from the two stars β and α at the mouth of Ursa major and extend to the other side five times away from them. There is a star that is not very bright. It is the alpha star of Ursa minor and the famous Polaris. Throughout the year, no matter where the handle of Beidou points, the connection between β and α always extends to Polaris. Therefore, these two stars were also called Polaris in ancient China.

The picture on the right shows the star map of Ursa minor. Connecting the main bright stars in the star map is more like a little Beidou than a little bear. The Big Dipper in Ursa minor is not only much smaller than that in Ursa major, but also the other seven stars are smaller than 4 except that α and β are second-class stars and γ is third-class. Unlike the Big Dipper in Ursa Major, the other six stars are all second-class except δ. So this little Big Dipper is far less eye-catching than the Big Dipper. People usually notice only the North Star.