Cassiopeia is a constellation in the northern sky named for the vain queen Cassiopeia, who boasted of her unequalled beauty in Greek mythology and was the mother of Andromeda. Cassiopeia was one of the forty-eight constellations listed by Claudius Ptolemy in the 2nd century BC, and it is now one of the eighty-eight contemporary constellations. Its unusual 'W' shape, formed by five bright stars, makes it instantly identifiable.
Cassiopeia is a constellation in the northern sky that may be seen all year round from latitudes north of 34°N. It can be seen at its clearest in the (sub)tropics from September to early November, and at low southern, tropical, latitudes of less than 25°S, it can be visible low in the North periodically. Alpha Cassiopeiae, or Schedar, is the brightest star in Cassiopeia, with a brightness of 2.2, though it is periodically eclipsed by the variable Gamma Cassiopeiae, which has a magnitude of 1.6. The yellow hypergiants Rho Cassiopeiae and V509 Cassiopeiae, as well as the white hypergiant 6 Cassiopeiae, are among the brightest stars in the sky. Tycho Brahe's supernova in Cassiopeia burned spectacularly in 1572. (Chrisholm 1911) Cassiopeia A is a supernova remnant that shines brightest in the sky at radio frequencies over 1 GHz. Exoplanets have been discovered in 14-star systems, one of which, HR 8832, is expected to have seven planets. Cassiopeia contains a rich part of the Milky Way, with several open clusters, young brilliant galactic disc stars, and nebulae. IC 10 is an irregular galaxy and the sole one in the Local Group of galaxies. It is the closest known starburst galaxy. |
Mythology
Cassiopeia, the queen of Aethiopia, is the name of the constellation. Cassiopeia was the mother of Princess Andromeda and the wife of King Cepheus of Aethiopia (Chrisholm 1911). Along with Andromeda, Cepheus and Cassiopeia were put near to each other among the stars. After enraging Poseidon with the statement that her daughter Andromeda was more beautiful than the Nereids, or that she was more lovely than the sea nymphs, she was sent to the sky as a punishment. (Chen 2007) Poseidon ordered Andromeda to be chained to a rock as prey for the monster Cetus, and she was compelled to circle about the North Celestial Pole on her throne, spending half of her time clinging to it, so she did not fall off. Perseus, the hero, saved Andromeda, whom she eventually married. (Chen 2007) Cassiopeia has been shown as a constellation in numerous ways throughout history. Al-Sufi depicted her as a queen of Persia, carrying a staff with a crescent moon in her right hand, wearing a crown, and riding a two-humped camel. She was depicted in France with a marble throne and a palm leaf in her left hand while holding her robe in her right. Augustin Royer's atlas, published in 1679, has this illustration. (Staal 1988)) The stars that make up the constellation Cassiopeia can be found in three places in Chinese astronomy: the Purple Forbidden Enclosure (紫微垣, Zǐ Wēi Yuán), the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ), and the White Tiger of the West (西方白虎, Xī Fāng Bái Hǔ). Several figures were seen by Chinese astronomers in what is now Cassiopeia. The constellations Kappa, Eta, and Mu Cassiopeiae created the Bridge of the Kings, which, when combined with Alpha and Beta Cassiopeiae, formed the mighty chariot Wang-Liang. Gamma Cassiopeiae, often known as "Tsih," the Chinese term for "whip," represents the charioteer's whip. (Staal 1988) Cassiopeia was associated with Sharmishtha in Hindu mythology, who was the daughter of the mighty Devil (Daitya) King Vrishparva and a friend of Devayani (Andromeda). Llys Dôn (meaning "The Court of Dôn") is the old Welsh name for the constellation in Welsh mythology. Caer Gwydion ("The Fortress of Gwydion") is the traditional Welsh name for the Milky Way, whereas Caer Arianrhod ("The Fortress of Arianrhod") is the constellation of Corona Borealis. (Squire 2013) Various Biblical figures were represented among the constellations of Cassiopeia in the 17th century. Bathsheba, Solomon's mother; Deborah, an Old Testament prophet; and Mary Magdalene, a disciple of Jesus, were among them. (Staal 1988) In some Arab atlases, a figure is known as the "Tinted Hand" appeared in the stars of Cassiopeia. This is claimed to symbolise a woman's hand coloured red with henna, as well as Muhammad's daughter Fatima's bloodied hand α Cas, β Cas, γ Cas, δ Cas, ε Cas, and η Cas. The arm is made up of the stars α Per, γ Per, δ Per, ε Per, η Per, and ν Per (Staal 1988) The Camel was another Arab constellation that included Cassiopeia's stars. It had a head made up of stars from Perseus and Andromeda; a hump made up of Beta Cassiopeiae; a body made up of the rest of Cassiopeia, and legs made up of stars from Perseus and Andromeda. (Staal 1988) In some civilizations, the motif includes a hand or moose antlers. (Ptak 1998) The Sámi, for example, see the W of Cassiopeia as an elk antler. The five major stars were also seen as five reindeer stags by the Chukchi of Siberia. (Staal 1988) Cassiopeia was seen as part of a large porpoise constellation by the Marshall Islanders. Cassiopeia's major stars make up its tail, Andromeda and Triangulum make up its body, and Aries makes up its head. (Staal 1988) Alpha, Beta, and Gamma Cassiopeiae were named in Hawaii. Poloahilani was the name of the Alpha Cassiopeiae, Polula was the name of the Beta Cassiopeiae, and Mulehu was the name of the Gamma Cassiopeiae. The Pukapuka people saw Cassiopeia as a separate constellation known as Na Taki-tolu-a-Mataliki. (Makeemson 1941) |
Characteristics
Cassiopeia is the 25th largest constellation in the sky, covering 598.4 square degrees and so 1.451 percent of the sky. It is bordered on the north and west by Cepheus, on the south and west by Andromeda, on the southeast by Perseus, on the east by Camelopardalis, and on the west by Lacerta. The International Astronomical Union selected the three-letter abbreviation "Cas" for the constellation in 1922. (Russell 1922) A polygon of thirty segments defines the official constellation borders, which were established by Belgian astronomer Eugène Delporte in 1930. The right ascension coordinates of these borders are between 00h 27m 03s and 23h 41m 06s in the equatorial coordinate system, while the declination coordinates are between 77.69° and 46.68°. Because of its location in the Northern Celestial Hemisphere, observers north of 12°S may see the entire constellation. It is circumpolar (that is, it never sets in the night sky) to watchers in the British Isles, Canada, and the northern United States since it is high in the northern sky. (Arnold et al., 1999) |
Deep-sky objects
IC 1848 – Soul Nebula with small open cluster – Emission Nebula
IC 1805 – Heart Nebula – Emission Nebula
Messier 52 – M52 – Open Cluster
Messier 103 – M103 – Open Cluster
NGC 457 – Open Cluster
NGC 663 – Open Cluster
3C 10 – Supernova Remnant – Radio spectrum only
NGC 185 – Dwarf Elliptical Galaxy – type E0 – Gravitationally bound to M31 (Andromeda Galaxy – Levy 2005)
NGC 147 – Dwarf Elliptical Galaxy - Gravitationally bound to M31 (Andromeda Galaxy – Levy 2005)
IC 10 – Irregular Galaxy
Main stars – 5
Bayer stars – 53
Stars with planets – 14
Stars brighter than magnitude 3.0 – 4
Stars within 32ly – 7
Bordering
constellations
Camelopardalis
Cepheus
Lacerta
Andromeda
Perseus
Meteor showers
Perseids - Mid-July to late- August - 60 per hour
IC 1848 – Soul Nebula with small open cluster – Emission Nebula
IC 1805 – Heart Nebula – Emission Nebula
Messier 52 – M52 – Open Cluster
Messier 103 – M103 – Open Cluster
NGC 457 – Open Cluster
NGC 663 – Open Cluster
3C 10 – Supernova Remnant – Radio spectrum only
NGC 185 – Dwarf Elliptical Galaxy – type E0 – Gravitationally bound to M31 (Andromeda Galaxy – Levy 2005)
NGC 147 – Dwarf Elliptical Galaxy - Gravitationally bound to M31 (Andromeda Galaxy – Levy 2005)
IC 10 – Irregular Galaxy
Main stars – 5
Bayer stars – 53
Stars with planets – 14
Stars brighter than magnitude 3.0 – 4
Stars within 32ly – 7
Bordering
constellations
Camelopardalis
Cepheus
Lacerta
Andromeda
Perseus
Meteor showers
Perseids - Mid-July to late- August - 60 per hour