Why does Polaris not move while other constellations revolve around it?

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Analysis:

The Polaris is obviously motionless from the earth, because it is almost "above" the straight line of the earth's rotation axis, and all the stars in the northern sky seem to rotate around it. So it can be measured as an excellent fixed point for sacred navigation. The use of this star was confirmed in ancient times, because it was found to represent Assyrian slate in early knowledge. At present, Polaris is slightly closed at 1. From the rotating rod, so around the rod in a small circle about 2 diameters. Only do Polaris twice every 24 hours to accurately determine the true northern azimuth; The rest of the time, this is the only plan that must be revised by using the form.

Although Shakespeare is like Polaris, due to precession, other stars in the northern hemisphere are and may become Polaris again. Tens of thousands of years to write "I am as constant; Thuban is a star in the past and Vega will be a star in the future.

It's easy to find that Polaris is catching up with Dubhe from Merak (and Ursa Major, also called tip), and the two stars are at the bowl end of the Big Dipper. You can also follow the central idea of Cassiopeia W shape.

Polaris's reputation as a Polaris has been continuously misunderstood as the brightest star in the sky. Although Polaris is a relatively bright and conspicuous star, it is far from the brightest; This is actually the brightest star of 5 1. The brightest star in the sky (except the sun) is Sirius. View a list of the brightest stars.

According to the measurement of Hipparcos satellite, Polaris is 43 1 light-year away from the Earth (132 parsec). This is a F7 super-large (Ib) or bright giant (ii) with two smaller partners: a F3 v main sequence star with about 2000 astronomical units and a close partner in a semi-principal axis orbit with 5 astronomical units. The main star is the Cepheid variable of population II, and the pulse makes it circulate smoothly. About 1900 years, stars change between 8% brighter and 8% darker than their average luminosity (0.15 huge total * * *), with a period of 3.97 days. Now (2004), the change from peak to trough is about 2%. This star is also about 15% brighter than 1900 (on average); Since then, the cycle has been extended by about 8 seconds every year. According to a recent research report, according to scientific advice, Polaris is now 2.5 times brighter than when Ptolemy observed it. Astronomer Edward Gyanen and he said, "If we think that this remarkable sum of change rates records that they are true, these changes are greater than those predicted by the current theory of stellar evolution" is 100 times.

There is no real South Star. This naked-eye star is the closest to the south antenna, which is the dim sigma code Octantis. However, the bright Southern Cross (critical moment) refers to the yearning for the southern antenna.