Introduction to pegasus

Pegasus is the seventh largest constellation in the whole day. In the autumn night sky, you can often see four bright stars arranged in a slightly longer square, which is called "Pegasus-Fairy Square". The star in the northeast corner of the box is the brightest alpha star in Andromeda, and this alpha star and some stars in the northeast corner are Andromeda. A large part of the starry sky in the square and west is Pegasus, which is one of the six "royal constellations". Extending from the west side of "Flying Horse-Fairy Box" to the south for about 3 laps, you will meet the brightest star in the southern night sky in autumn-Beiluoshimen; Go north for about four laps, and you will meet the North Star. From the east side of the "Flying Horse-Fairy Box", it extends to the south for the same length, and then reaches the vicinity of vernal equinox on the ecliptic. Every spring equinox (that is, March 20th or 2 1 day), the sun passes through this point; It extends about four times to the north, which is the position of the North Pole star.

Pegasus is closer to the ecliptic. Aries and Pisces in the east and Aquarius and Capricorn in the southwest are all constellations on the ecliptic. The four stars that make up the main body of Pegasus are located at the four corners of a square. China is called Virgo I, Virgo II, Gekko I and Gekko II. Among them, the second one is the brightest. Although it belongs to Andromeda (the alpha star of Andromeda), it is actually shared by Pegasus and Andromeda. More importantly, whenever the flying horse reaches the zenith in autumn, the four sides of this quadrilateral just represent one direction, which is simply a "natural locator". In fact, it can not only locate but also find many other constellations through it. Such as Aquarius, Andromeda, Cygnus and so on.

The position of this square in the sky is very important, because each side of it represents a direction. When you see this square, you can determine the four directions of southeast and northwest. The east side of the square is generally on the line between vernal equinox and the North Celestial Pole, which extends the same length from this side to the south, that is, vernal equinox; Extending about four times the distance to the north, that is the North Star. The west side of the square extends about 3 times to the south, and the bright star of the southern fish constellation falls on the north gate; Extend about four times the distance to the north, and you will also find the North Star.

In autumn, the North Star in the Big Dipper is very low in the northern sky, and it is not easy to be found, even in the south of China. Therefore, it is very useful to find Polaris through the autumn quadrangle of Pegasus. In addition, the lines from Gamma Pegasus and Alpha Andromeda to Polaris are near the 0 red meridian. Through this line, we can roughly estimate the longitude of the celestial bodies we are interested in in in the autumn sky.