Information about Ursa minor

Abbreviation: UMi

Approximate area: 256 square degrees

A constellation suitable for spring observation, where the famous Polaris is located.

English: Ursa minor, Ursa minor or Ursa minor.

Bright star:

Ursa minor (Polaris): magna.2,1ra: 02h31m48.28sdec:+8915' 50.7 ".

Kochab): magna.2 ra:14h50m42.39 sdec:+7409'19.7 ".

Ursa minor: magna.3,1ra:15h20m43.73sdec:+7150' 02.5 "

Ursa minor is not a bright constellation, but its Polaris (Alpha Ursa minor) is very famous. Polaris is the main star of this constellation.

Polaris is a yellow Supergiant star 600 light years away. In fact, Polaris is not on the north celestial pole, but it is less than one degree away from the north celestial pole on the celestial sphere. Now it is approaching the north celestial pole, but it will start to move away from it in 2 100 years. Polaris is a variable star, and its magnitude changes from 2, 1 to 2, 2 in a four-day period. Polaris has a companion star, about 9.

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.

The position of the earth's rotation axis in the sky is very stable, so people define the direction of the earth's rotation axis in the sky as south and north. Polaris is just in the direction of the earth's rotation axis, so in ancient times, when people sailed in the sea and trudged in deserts, forests and wilderness, they always turned to it to indicate the direction. People worship it so much that China even regarded it as a symbol of ancient emperors. Even in today's highly developed science and technology, Polaris still has very important applications in astronomical measurement, positioning and many other aspects.

In fact, Polaris is not entirely in the North Pole. It is far from the North Pole 1, but there is no other star closer to the North Pole, so it is regarded as the nearby North Pole. If we stand at the north pole of the earth, the Polaris is directly above us. In other parts of the northern hemisphere, people see that Polaris is always in that position due north. Moreover, due to the rotation and revolution of the earth, the constellations in the northern sky seem to revolve around the North Star every day and every year. In particular, the spoon mouth points to the big dipper of Polaris, and it never tires and never stops. The ancients in China were deeply touched by this and wrote in the Book of Changes, "Heaven is healthy, and gentlemen are constantly striving for self-improvement." If it makes sense.

History and myth

Two famous myths and legends about Ursa minor are as follows:

One theory is that Ursa minor represents one of the goddesses who raised Zeus.

Another way of saying it is that Ursa minor represents Akka, the son of Zeus. Once, Zeus fell in love with a Zhu Fu named Caristo, and soon Caristo became pregnant and gave birth to Zeus' son Aka. After learning this, the angry diva Hera changed karis into a big bear, and she had to live in the forest. Many years later, Caristo's son Aka grew up and became an excellent hunter. On this day, Aka was hunting in the forest. Caristo recognized her son, but forgot that she was a bear. She ran to him involuntarily. However, Aka didn't know that this terrible bear was his mother, so he raised his pike and pointed it at the bear. At this dangerous moment, Zeus quickly turned Aka into a bear. Achatz, who became a bear, recognized his mother, thus avoiding a tragedy of killing relatives. Later, Zeus took two bears to heaven and gave them two glorious positions among the stars, Ursa Major and Ursa Minor.