So how do we determine the location of a location? There are various methods, such as using the midday sun orientation to determine the local south or the north (relatively cumbersome, need to observe the shadow of the geographical things to calculate and determine), if we are in the northern hemisphere, we can also use the North Star to quickly determine the north position . The North Star is the northward extension of the Earth's rotation axis. The star pointed to it is also called "Gang Chenyi". It is about 434 light years away from the Earth and has a diameter of about 52 million kilometers, about four times the mass of the Sun. Because the Polaris is far from the Earth, its apparent magnitude is about 1.97, which doesn't look very bright.
Although the Polaris is not very bright, it is very special in the sky. Because the North Star is located on the northward extension of the Earth's axis, the position of the North Star in the sky is almost unchanged during the Earth's rotation, and other stars in the sky. They will rotate as the Earth rotates, and the center they surround is the "North Star." Therefore, in the sky, we only need to find the North Star, we can determine the local orientation, toward the North Star, pointing to the north direction, and then rotate 90 ° clockwise, you can get the "Southeast West" three directions.
Big Dipper and Polaris
We look for the North Star in the sky and can use the position of the Big Dipper to determine it (as shown above). Of course, the use of Polaris for azimuth positioning can only be found in the northern hemisphere. If it is located in the southern hemisphere, the Earth's spherical surface will obscure the line of sight and the North Star cannot be seen. In addition, the use of Polaris can also determine the latitude of the location, the angle between the star and the ground plane in the sky is called the "elevation angle", then the "the number of elevation angles of the North Star" observed in a certain place is the latitude of the place.
Can you find the North Star?xx