The third constellation of Polaris: Cassiopeia

Cassiopeia, one of the northern constellations, is far away from Ursa major and close to the north celestial pole. You can see it all year round, especially in autumn night.

Cassiopeia is easy to tell. It is M(W)-shaped.

Cassiopeia is almost comparable to the Big Dipper. Cassiopeia has more than 100 stars that can be directly seen by the naked eye, but it is as bright as Ursa Major, with six to seven stars. Three of them are secondary stars and two are tertiary stars. They form an obvious capital letter "W" shape, and the opening direction is the direction of Polaris, which is the most important symbol to identify Cassiopeia.

The most interesting thing is the Y star in Cassiopeia, which is a blue giant, and its brightness changes with the expansion of the star gas layer. Cassiopeia has several famous star clusters, such as M52 and NGC457.

Cassiopeia and the Big Dipper are far opposite each other across the Polaris. When Cassiopeia rises to the zenith in autumn, the Big Dipper runs to the lowest place in the sky. You can't see it in the south of China at this time. When we can't see the Big Dipper, we can also find the North Star. We can connect the midpoint between the δ star and ε star and γ star in Cassiopeia, and then extend northward to find Polaris.

Cassiopeia is one of the 88 modern constellations listed by the International Astronomical Union, and Cassiopeia is also one of the 48 constellations listed by the ancient Greek astronomer Ptolemy.

The five brightest stars in Cassiopeia make up a W (or M). It is close to the north celestial pole. At high latitudes, it doesn't set all night, and it is opposite to the Big Dipper, so Cassiopeia is also one of the polar constellations.

As early as the Ming Dynasty, it was recorded that1572+065438+1October1day, a bright star suddenly appeared in Cassiopeia, which could be seen in broad daylight. It lasted for three weeks before it began to darken slowly, and 17 months later was seen. This phenomenon is what we call "supernova explosion" in modern astronomy. The residue after supernova explosion will form a powerful radio source with antenna radio wave radiation.

Constellation myth

Legend has it that Cassiopeia is the incarnation of Cacio Paya, the queen of King Kaifus of Ethiopia. Because the Queen often boasts in front of people that she and her daughter (Andlau Moda) are the most beautiful women in the world, even Poseidon's daughter Nereid can't compare with her. Her words angered Poseidon and wanted to blame her. The king and queen were so afraid that they had to give their daughter to Neptune. Fortunately, they were saved by the hero Poerxiusi. Later, Poseidon was moved by them, lifted the king and queen to the sky and turned them into constellations. The queen boasted deeply in the sky and was very arrogant. So after she became Cassiopeia, she remained hands in the air, bent down to show her remorse, and turned around the North Celestial Pole forever. I believe people will forgive her ignorance.