What stars are motionless?

Polaris refers to the star closest to the north celestial pole, so Polaris is not always the same. At present, it refers to Gou Chenyi. About 434 light years away from the earth, it is a star with stable brightness and position that can be seen in the night sky.

Now Polaris is a bright star named Dog, and its western name is Dog Eye. This star is located at the tip of the bear's tail in Ursa minor. In English, Cynosure also means center of attraction, which means that the stars revolve around the hook.

Polaris is a bright star in the northern part of the sky, close to the north celestial pole and almost opposite the earth axis. Seen from the northern hemisphere of the earth, its position is almost unchanged, so it can be used to identify the direction. However, due to precession, Polaris is not a star whose position will never change, and it will be Vega by the year 14000. Every 25,800 years, Polaris will cycle. For example, during Magellan's voyage, Gouchen I was about 8 degrees from the North Pole, but today, Gouchen I is closer to the North Pole, with an angle difference of only 40'. According to the calculation of earth axis swing and stellar gravity, by 2 100, Gouchen-1 will reach the nearest position directly above the North Pole, only 28' away from the North Pole. So, I gradually hooked up.

Polaris is the brightest star in Ursa minor at present, that is, Alpha in Ursa minor. It is a yellow giant with a spectral type of F, about 434 light years away from the Earth, and its mass is about four times that of the sun. It is a bright star far away from the earth, at the tip of the bear's tail in the constellation diagram. Gou Chenyi is also a star of underworld nature.

Connect a straight line between Tian Xuan and Shu Tian at the front end of the Big Dipper, and then extend the distance five times to Shu Tian. You will meet a bright second-class star, which is Gou Chenyi. This is the easiest way to find Gou Chenyi.

Polaris (Gouchenyi) is also a three-in-one system. The distant companion star (Polaris B) can be clearly observed with a small telescope, while the nearby companion star (Polaris) is too close to Polaris (the apparent distance is only 0.2 ",the actual distance is 18.5) and too dark to see. It was not until early August 2005 that Hubble captured its image. Polaris is very close to the north pole of the earth in the sky. Therefore, it always seems to be in the northern sky. It is because of its important position that it is famous. Because of the special name Polaris, many people think that Gouchenyi is very bright, but in fact, under the ordinary weather in the city at night, the brightness of Gouchenyi has basically reached the resolution limit of the human eye, which is why many people read popular science books when they were young and knew about Polaris, but they could not find it in the northern sky. Unless the weather is fine at night, it is difficult to find Gou Chenyi directly.

keep a secret

Because the earth rotates around the earth axis, and Polaris is very close to the north extension line of the earth axis, Polaris is almost motionless in the sky at night, with its head tilted to the north, so it can indicate the north. Although the tilt direction of the earth's axis will change because the earth revolves around the sun all year round, the distance between Polaris and the earth is much larger than the radius of the earth's revolution, so the change of the earth's axis caused by the earth's revolution can be ignored. So all the year round, we see that the position of Polaris in the sky seems to be motionless in the north. In fact, we just can't observe the subtle changes with the naked eye, and we feel that the earth axis always points to Polaris.

function

Polaris is a very important indicator of field activities and ancient navigation direction, and it is also a constellation that can tell the direction from small to stargazing to large to astrophotography, and the equatorial observatory in the observation room accurately locates it. Because Polaris is closest to true north, people on earth have been navigating by its starlight for thousands of years.

Star-seeking method

You can find the Big Dipper first, and then find the North Star through the Big Dipper. The Big Dipper is a part of Ursa major. Graphically, the Big Dipper is located at the back and tail of Ursa Major. Of these seven stars, six are secondary stars and one is tertiary. Through the connection of two stars (Shu Tian and Tian Xuan) in Doukou, Polaris was discovered after extending in the direction of Doukou for about five times. Beginners can look for other constellations in turn from the Big Dipper.

Will the pattern of the Big Dipper never change? Will it always be a "tool" to find the North Star? Of course not. Everything in the universe is moving and changing, and stars are no exception. As the stars are also moving, the pattern of the Big Dipper is certainly changing. These seven stars are at different distances from us. At 100 light-years, their respective speeds and directions are different. Astronomers have calculated that the pattern of the Big Dipper seen 654.38 million years ago and the pattern seen 654.38 million years later are very different from today's.

In addition, the celestial ridge of the Big Dipper, the intersection of Tian Quan and Kaiyang and Yaoguang are connected with Yuheng, extending seven times, and Polaris can also be found. The intersection of the left and right sides of the W-shaped Cassiopeia is five times longer than the middle star, which is also the position of the North Pole star.

symbolic meaning

It is precisely because the position of the North Star is relatively stable and unchanged that it gives people a sense of loyalty and has its own position. From the perspective of life, Polaris has the significance of leading us to our goals, just as it can tell us the direction.

From the perspective of love, Polaris symbolizes firmness, persistence and eternal protection. If it is anthropomorphic, then it must have a commitment to the stars near it, otherwise it will not insist on guarding, such as the moon. Although far away, Polaris is still guarding. So Polaris is firm, symbolizing that it will never change!

Polaris once said to the earth, "If you get lost, look up at me, and I will wait for you here forever." So people who get lost will look up at the North Star.