CASSIOPEIA

The constellation of Cassiopeia
The constellation of Cassiopeia.
Roberto Mura - Own work,
CC BY-SA 3.0, wikimedia
Responsive image
Map of the constellation of Cassiopeia.
CC BY-SA 3.0, wikimedia

Cassiopeia is an easy constellation to see in the skies thanks to its 5 brightest stars that form a well defined ‘W’ in spring and an ‘M’ in autumn. For those living at the middle latitudes in the Northern hemisphere, the constellation is circumpolar and can be seen in every month of the year. Neophyte stargazers use it as a constant when trying to recognize other constellations.

Responsive image
Cassiopeia, the vain queen sitting on the throne, in the Atlas Coelestis by John Flamsteed.
Public domain, wikimedia

Cassiopeia was the wife of the King of Ethiopia, Cepheus. The King and Queen are now close together among the stars, the only couple present in the skies. Cassiopeia plays a big part in the story of Andromeda and Perseus. The Queen, boasting that she was more beautiful than the sea nymphs, the Nereids, enraged the sea nymphs and they asked Poseidon to intervene. A terrible sea monster called Cetus was sent to ravage the sea coasts of the African Horn. The only solution to the problem was to sacrifice Cassiopeia’s daughter, Andromeda, who was subsequently chained to a rock. She was saved by Perseus who turned the sea monster to stone by showing him the head of Medusa.

Gamma Cassiopeiae is potentially the brightest star in the constellation but does not have a proper name perhaps because it is a variable star where its luminosity oscillates from the first to the third magnitude unpredictably fading and brightening. It is 550 light-years from us and has a mass which is 17 times that of the Sun and it is 34,000 times brighter than the Sun.

The Alpha star Shedir is 800 times brighter than the Sun and is an orange giant 230 light-years from Earth. It is the heart of the constellation even though the correct translation of its Arabic name is ‘the breast’.

The Beta star Caph is fairly near the Solar System just 55 light-years away and is 28 times brighter than the Sun. It is in a phase of evolution in that it is about to leave main sequence to evolve into a red giant.
Cassiopeia can be found along the winter branch of the Milky Way and is therefore rich in deep-sky objects.
Responsive image
M52, a brilliant open cluster.
Public domain, wikimedia

M52 is the open cluster easier to see, it is 4,500 light-years from us and is made up of young stars. M103 needs to be seen through a telescope to make out its triangular shape and the assorted colors of its stars. It is 9,400 light-years away.

Responsive image
NGC 7789
Roberto Mura, Own work.
CC BY-SA 3.0, wikimedia

A telescope is needed to see NGC 7789, an open cluster rich in stars, the most spectacular in the Cassiopeia constellation. It is thought to be made up of 700 components and is 7,600 light-years from Earth.

Responsive image
the Bubble Nebula.
Original uploader was Vanderbei at en.wikipediaderivative work: Dereckson (talk) - Ngc7635.jpg,
CC BY 3.0, wikimedia

The nebula NGC 7635, also called the Bubble Nebula, is stunning when photographed. This bubble of gas is literally blown by the stellar wind of a young star giving it its shape. It is thought to be 11,000 light-years from the Solar System.

Northern Hemisphere: Cassiopeia is visible in every month of the year. In the early evening in Spring it is low towards the north, north-east in summer, high just under zenith in autumn and north-west in winter.

Southern Hemisphere: the constellation is not very visible or not at all visible. At the southern middle latitudes, between the beginning of October and the end of December, right after sunset, it can be found above the horizon towards the north.