Introduction to Cassiopeia

Cassiopeia is a constellation comparable to the Big Dipper. There are at least one hundred stars that can be seen clearly with the naked eye, but only six or seven are particularly bright. Among them, three second-class stars and two third-class stars form an obvious English capital letter W, which is the most important symbol to identify Cassiopeia. Cassiopeia can also be found in this way: extend the connection line between the celestial pole of the Big Dipper and the Polaris to the south by about the same length, and you can reach Cassiopeia on the "shore" of the Milky Way. Extending the autumn quadrangle to the north, the gamma star Pegasus and the alpha star Andromeda have a bright 2m star, which is the beta star Cassiopeia (Polaris can be seen farther north along this line). The five brightest stars in Cassiopeia, β, α, γ, δ and ε, form the shape of an English letter "M" or "W", which is the most prominent symbol of Cassiopeia. The most interesting thing is Cassiopeia γ (Chinese: Ce), a blue giant whose brightness changes with the expansion of the stellar gas layer. Cassiopeia also has several famous star clusters, such as M52 and NGC457.

The "W" of Cassiopeia is far away from the Big Dipper, so when Cassiopeia rises to the zenith in autumn, the Big Dipper is at the lowest place in the sky, even in the south of China. Without Beidou, we can connect the midpoint of δ star with ε and γ star and extend northward to find Polaris. The Polaris Cassiopeia stands for Queen Cassiopeia of Ethiopia. It is one of the 88 modern constellations of the International Astronomical Union and one of the 48 constellations listed by Ptolemy, an ancient Greek astronomer.

Cassiopeia is an easily recognizable constellation. Its five brightest stars form a very unique W-shape. Because it is not far from the north celestial pole, this constellation will not fall all night at high latitudes, and compared with the Big Dipper, the Big Dipper is also one of the polar constellations.