Constellation Cassiopeia

How to Recognize the Constellation Cassiopeia in the Night Sky

Constellation Cassiopeia
Jose Juan Gutierrez's image for:
"How to Recognize the Constellation Cassiopeia in the Night Sky"
Caption: Constellation Cassiopeia
Image by: stanlekub
© Creative Commons Attribution-Share Alike 3.0 Unported license.

Cassiopeia is one of the 88 constellations that have been classified in the night sky. Cassiopeia is best recognized by its resemblance to the letter w or M, depending on the time of the year. Given there are clear skies, Cassiopeia can be seen high in the sky throughout much of the year. Cassiopeia contains some interesting deep sky objects and many stars. The constellation Cassiopeia was named after the queen of Ethiopia.

The five stars forming Cassiopeia are all above third magnitude. These include Alpha Cassiopeia, which is a double star of magnitude 2.2; Beta Cassiopeia, which is a white star with magnitude 2.3; Gamma Cassiopeia, which is a variable star, with a minimum magnitude of 3.0 and a maximum magnitude of 1.6; and Delta Cassiopeia, which is an eclipsing star with variable magnitudes of between 0.1 and 2.7. The constellation Cassiopeia contains a number of fainter stars, all which can be detected with high resolution telescopes.

Deep sky objects in Cassiopeia

The constellation Cassiopeia contains some deep sky objects known as messier objects, including M52 and M103. Both of these Messier objects are open clusters, containing several stars each. Cassiopeia contains two supernova remnants. One called Tycho´s Star, which was observed by Tycho Brahe in 1572; the other known as Cassiopeia A, a bright radio source supernova remnant. NGC 457, which contains more than one hundred stars, was discovered in 1787 by William Herschel.

Where is Cassiopeia Located in the sky?

The constellation Cassiopeia is a circumpolar constellation, that is to say, it is located close to Polaris, the North Star and can be seen throughout most of the year in the night sky in the northern latitudes. Cassiopeia is between 0-2 hours right ascension and between 55 and 65 degrees declination. This constellation also is situated about 30 degrees south of Polaris. Cassiopeia lies between the constellations Andromeda to the south and Cepheus to the north.

How do you recognize Cassiopeia in the sky?

Cassiopeia is best recognized in the night sky by its bright stars that form the shape of a w. it is also recognized because it lies on the band of the Milky Way and contain many deep sky objects and other dim stars within. Another recognizable feature of Cassiopeia is that is situated at the same distance that the Big Dipper is situated from Polaris, although in the opposite direction.

How to find Cassiopeia in the night sky?

You can find Cassiopeia in the night sky locating the Big Dipper, which is another circumpolar asterism in the sky, and then trace an imaginary line from the bowl´s outer stars all the way to Polaris and continue ahead another similar distance. You may also use the aid of a planisphere, which is a map of the stars and constellations. A planisphere contains a movable disk with an orifice through which you can observe a portion of the sky. A planisphere lets you see the stars as you might see them in the sky. Once you have located a sky object on the planisphere, you can locate it easily in the night sky.

Cassiopeia took its name after the queen of Ethiopia. According to the story, Cassiopeia was Cepheus´ wife and she had a daughter named Andromeda. Cassiopeia was placed in the sky as a punishment for boasting that she and her daughter Andromeda were prettier than the Nereids. Phi Cassiopeiids is a meteor shower radiating from Cassiopeia and occurring during the month of December. According to, Cassiopeia is not far from Polaris, the North Star and is easy to recognize for its W or M shape, depending on the time of year.

More about this author: Jose Juan Gutierrez

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