There are countless stars in the night sky, but not many of them we can name.

But if someone asks, what are the stars of the big dipper? How big are they? How far away are they from the earth? Not many people would be able to answer this question clearly, but that's okay, so let's fill in the blanks about the big dipper.

The big dipper is located in the constellation ursa major, and under good observing conditions we can find them almost every day in the night sky of the northern hemisphere. These seven shining stars form a distinctive spoon shape and are very easy to recognise.

They are named in this order from the first star at the top of the 'spoon' to the end of the 'spoon': Tianshu, tianxuan, tiangui, tianquan, yuheng, kaiyang and yaoguang.

Tianshu

At a distance of about 123 light-years from the earth, tianshu is the farthest star from the earth of the big dipper, with a mass about 4.25 times that of the sun and a luminosity 316 times that of the sun.

As the ascendant has now evolved to the giant stage, its surface temperature is only 4660 k and its volume cannot be precisely determined, although it is certain that its radius is much larger than that of the sun. In addition, the ascendant has a companion star with a mass about 1.6 times that of the sun, a distance of about 23 astronomical units between them and an orbital period of about 44.4 years.

Tianxuan

At a distance of about 79.4 light-years from earth, with a radius of about 2.84 times that of the sun and a mass of about 2.7 times that of the sun, tianxuan is a subgiant star about to enter the giant stage, with its core largely depleted of "Hydrogen fuel" And currently in the "Hydrogen shell layer fusion "Its surface temperature is similar to that of the sun, and its luminosity is 63 times that of the sun.

Tiangui

Breguet is about 83 light years from earth, has about 2.94 times the mass and 3.04 times the radius of the sun, its surface temperature is 9355 k and its luminosity is 65 times that of the sun. It is worth noting that past observations show that breguet has a companion star with a mass about 0.79 times that of the sun, but this companion star has not been observed in any of the many recent observations.

Tianquan

Tianquan is the famous star "Wenqu", which is also the faintest and least massive of the big dipper stars. Its distance from the earth is about 80.5 light years, its mass is about 1.63 times that of the sun, its radius is about 1.4 times that of the sun, its surface temperature is 8910 k, and its luminosity is only 14 times that of the sun. It should also be noted that tianquan also has a companion star, and two of them at that, but they are so faint that astronomers do not know much about them yet.

Jade helm

Jade helm is about 82.6 light years from earth, has a radius about 4.14 times that of the sun, a mass about 2.91 times that of the sun, a surface temperature of 9020 k, and a luminosity 102 times that of the sun. Although not as luminous as the ascendant, yu heng is the brightest star of the big dipper in our earthly eyes because it is closer to the earth. Astronomers have long suspected that yu heng also has a companion star, but none has been found so far.

Kaiyang

Kaiyang is about 82.9 light-years away from the earth, has a mass about 2.2 times that of the sun, a radius about 2.4 times that of the sun, a surface temperature of 9000 k, and a luminosity 33 times that of the sun. If the observing conditions are good, we can distinguish, with the naked eye alone, the presence of a faint star in the vicinity of kaiyang; in fact, there are four other stars in this region, which together form a hexagonal system.

Yawning

Of the seven stars of the big dipper, all are in the main sequence stage, except for tianshu and tianxuan, while yaoguang is the youngest, as it is only about 10 million years old. In addition to this, yaoguang has three other "Big dipper bests": The largest mass (6.1 times the mass of the sun), the highest surface temperature (15540 k), and the strongest luminosity (594 times the sun's luminosity).

However, as the radius of the dipper is only 3.4 times that of the sun, and because it is also relatively far away from the earth (about 104 light years), it is only the third brightest of the big dipper stars in our eyes (the first and second being yu heng and tian shu respectively).

The big dipper is not static, and as the earth moves, their relative positions in the night sky change regularly, as if the big dipper were a "Spoon" Spinning in the sky, and it is interesting to note that when the "Spoon handles" Are pointing interestingly, when the "Spoon handles" Are pointing to the north, south, east and west, the corresponding seasons on earth are spring, summer, autumn and winter.