Constellation Cassiopeia (Seated Queen)

Cassiopeia: IAU Constellation Map [150]


Cassiopeia belongs to the circumpolar constellations and is very noticeable. The five brightest stars form a spooky 'W' that is open to the north. With her husband Cepheus on the western side, she looks at her son-in-law Perseus and her daughter Andromeda in the south. The constellation is in the band of the Milky Way, roughly opposite its center and thus contains a number of open star clusters. The constellation has an area of 598 square degrees and its center culminates around midnight on October 9th. [9, 15]

Stars with Proper Names [154]
α Cas Shedir, Schedar, Schedir
β Cas Caph, Chaph, Kaff, Al Sanam Al Nakah
δ Cas Ruchbah, Rucba, Rucha, Ksora
ε Cas Segin, Ruchbah
η Cas Achird
θ Cas Marfak
μ Cas Marfak
Data for constellation Cassiopeia [150]
IAU NameCassiopeia
IAU GenitiveCassiopeiae
IAU Abbr.Cas
English NameSeated Queen
Opposition8 October
Season (47° N)July … January
Right Ascension22h 57m 05s … 03h 41m 14s
Declination+46° 40' 33" … +77° 41' 32"
Area598 deg2
Neighbours (N↻)Cep, Lac, And, Per, Cam

Deep-Sky Object Descriptions


Cassiopeia: Constellation Cassiopeia with Heart and Soul Nebula (IC 1805 and IC 1848), double cluster Chi and h Persei (NGC 884 and NGC 869) and Pacman Nebula (NGC 281); Tamron 85 mm 1:1.8 Di VC USD at f/2.8; Canon EOS 6Da; iOptron SkyGuider Pro; 77x2 min @ 800 ASA; Bern, Elfenau, 561 m AMSL; © 11. 10. 2017 Manuel Jung [45]

Mythology and History

In Greek mythology, the beautiful but also arrogant Cassiopeia represented the queen of Ethiopia, part of the royal family of heaven. In the sky she appears sitting on a chair. Her husband was King Cepheus and her daughter was Princess Andromeda. Cassiopeia insulted the beautiful daughters of the ancient sea god Nereus. She boasted that she was more beautiful than her. The nymphs complained to Poseidon, god of the seas, who thereupon sent the sea monster Cetus to destroy the Ethiopian coast and demanded Kassiopeia's daughter as a sacrifice. Andromeda was freed by Perseus.

Despite her daughter's rescue, she was reluctant to give Cassiopeia away. When the celebration of the wedding was interrupted by the intrusion of an armed band secretly sent by Cassiopeia and the leader of this group, Agenor, claimed the hand of Andromeda for himself, a battle broke out. Perseus killed a large number of his opponents, but the majority of his enemies were so powerful that he had to get the Gorgon head to put an abrupt end to the ghost. Two hundred of his enemies turned to stone in horror at the sight of Medusa's severed head. As if by magic, the wild noise of the battle faded away with one stroke. In this silence Poseidon had placed Cepheus and Cassiopeia under the stars. Cassiopeia had first been seen tied up in a market basket as a punishment, which in some seasons even stood upside down in the sky and showed her in a most uncomfortable position, where she was also exposed to the cheap ridicule of the common people. Today, on the other hand, you often see her depicted on a throne chair, in keeping with the dignity of her person, but this too is sometimes tilted dangerously in the sky.

Constellation Cassiopeia
Constellation Cassiopeia: The bright star B Cassiopeiae is SN 1572 (Tycho Brahe's Supernova). Illustration from «Uranometria» by Johann Bayer, copper engraving by Alexander Mair, 1603 [28]

Cassiopeia and Cassiepeia, as this constellation is sometimes written, is one of the oldest and most famous. Because of its shape one sometimes speaks of Heaven-W or Heaven-M. The Romans and the Greeks interpreted the constellation as a woman sitting on an armchair, a throne and therefore called Mulier Sedis or simply Sedes. In the 17th century, when the church tried to Christianize the constellation figures, the constellation Cassiopeia became the sinner Mary Magdalene.

The constellation Custos Messium (The Harvester) used to exist between Cassiopeia and the Pole Star. However, this constellation is no longer recognized today. [20, 74]


  • [9] «Drehbare Sternkarte SIRIUS» von H. Suter-Haug; Hallwag-Verlag, Bern
  • [15] «Hartung's Astronomical Objects for Southern Telescopes» by David Malin and David J. Frew; Melbourne University Press 1995; ISBN 0-522-84553-3
  • [20] «Sternbilder und ihre Mythen» von Gerhard Fasching; Zweite, verbesserte Auflage; Springer Verlag Wien, New York; ISBN 3-211-82552-5 (Wien); ISBN 0-387-82552-5 (New York)
  • [28] «Uranometria omnium asterismorum continens schemata, nova methodo delineata aereis laminis expressa» Johann Bayer, Augsburg, 1603; DOI:10.3931/e-rara-309
  • [45] Astro-, Landschafts- und Reisefotografie sowie Teleskopbau, Manuel Jung;
  • [74] The Starry Sky: Cassiopeia by Deborah Byrd; Astronomy 9/94, p.63
  • [150] IAU: The Constellations, 11. Oktober 2020;
  • [154] Yale Bright Star Catalog, 15. Oktober 2020;