Cassiopeia (constellation)

Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars. It is bordered by Andromeda to the south, Perseus to the southeast, and Cepheus to the north. She is opposite the Big Dipper, and from northern latitudes can be seen at her clearest in early November.
==Notable features==
===Stars===
The four brightest stars of Cassiopeia are all brighter than the third magnitude. Alpha Cassiopeiae, traditionally called "Shedir", is a double star. The primary is an orange-hued giant of magnitude 2.2, 229 light-years from Earth. The secondary is widely separated from the primary and is of magnitude 8.9. Its traditional name means "the breast". Caph, designated Beta Cassiopeiae, is a white-hued star of magnitude 2.3, 54 light-years from Earth. The two other notably bright stars in Cassiopeia are both variable stars. Gamma Cassiopeiae is a shell star, a type of variable star that has a very high rate of rotation. This causes the star to be somewhat unstable and periodically eject rings of material. Gamma Cassiopeiae has a minimum magnitude of 3.0 and a maximum magnitude of 1.6; it is currently approximately magnitude 2.2. Delta Cassiopeiae, also known as "Ruchbah", is a Algol-type eclipsing variable star. It varies by 0.1 magnitudes around magnitude 2.7; its period is two years and one month. Ruchbah appears to have a blue-white hue and it is 99 light-years from Earth.
There are several dimmer single stars in Cassiopeia. Epsilon Cassiopeiae is a blue-white hued star of magnitude 3.3, 442 light-years from Earth. Rho Cassiopeiae is a semi-regular pulsating variable yellow-hued supergiant star, among the most luminous stars in the galaxy with a luminosity of approximately 500,000 solar luminosities. It has a minimum magnitude of 6.2 and a maximum magnitude of 4.1; its period is approximately 320 days. Rho Cassiopeiae is about 10,000 light-years from Earth.
Cassiopeia possesses several dimmer double stars and binary stars. Eta Cassiopeiae is a binary star with a period of 480 years. The primary is a yellow-hued star of magnitude 3.5 and the secondary is a red-hued star of magnitude 7.5. The system is 19 light-years from Earth. Iota Cassiopeiae is a triple star 142 light-years from Earth. The primary is a white-hued star of magnitude 4.5, the secondary is a yellow-hued star of magnitude 6.9, and the tertiary is a star of magnitude 8.4. The primary and secondary are close together but the primary and tertiary are widely separated. Sigma Cassiopeiae is a binary star 1500 light-years from Earth. It has a green-hued primary of magnitude 5.0 and a blue-hued secondary of magnitude 7.3. Psi Cassiopeiae is a triple star 193 light-years from Earth. The primary is an orange-hued giant star of magnitude 4.7 and the secondary is a close pair of stars that appears to be of magnitude 9.0.
===Deep-sky objects===
Because it lies in rich Milky Way star fields, Cassiopeia contains many deep sky objects, including open clusters and nebulae. 
Two Messier objects, M52 (NGC 7654) and M103 (NGC 581), are located in Cassiopeia; both are open clusters. M52, once described as a "kidney-shaped" cluster, contains approximately 100 stars and is 5200 light-years from Earth. Its most prominent member is an orange-hued star of magnitude 8.0 near the cluster's edge. M103 is far poorer than M52, with only about 25 stars included. It is also more distant, at 8200 light-years from Earth. Its most prominent member is actually a closer, superimposed double star; it consists of a 7th-magnitude primary and 10th-magnitude secondary.
The other prominent open clusters in Cassiopeia are NGC 457 and NGC 663, both of which have about 80 stars. NGC 457 is looser, and its brightest member is Phi Cassiopeiae, a white-hued supergiant star of magnitude 5.0. The stars of NGC 457, arrayed in chains, are approximately 10,000 light-years from Earth. NGC 663 is both closer, at 8200 light-years from Earth, and larger, at 0.25 degrees in diameter.
There are two supernova remnants in Cassiopeia. The first, which is unnamed, is the aftermath of the supernova called Tycho's Star. It was observed in 1572 by Tycho Brahe and now exists as a bright object in the radio spectrum. Within the 'W' asterism formed by Cassiopeia's five major stars lies Cassiopeia A (Cas A). It is the remnant of a supernova that took place approximately 300 years ago (as observed now from Earth; it is 10,000 light-years away), and 
has the distinction of being the strongest radio source observable outside our solar system. It was perhaps observed as a faint star in 1680 by John Flamsteed. It was also the subject of the first image returned by the Chandra X-Ray Observatory in the late 1990s. The shell of matter expelled from the star is moving at per second; it has a temperature of 30,000 degrees Kelvin on average.
NGC 457 is another open cluster in Cassiopeia, also called the E.T. Cluster, the Owl Cluster, and Caldwell 13. The cluster was discovered in 1787 by William Herschel. It has an overall magnitude of 6.4 and is approximately 10,000 light-years from Earth, lying in the Perseus arm of the Milky Way. However, its most prominent member, the double star Phi Cassiopeiae, is far closer - between 1000 and 4000 light-years away. NGC 457 is fairly rich; it is a Shapley class e and Trumpler class I 3 r cluster. It is concentrated towards its center and detached from the star field. It contains more than 100 stars, which vary widely in brightness.
Two members of the Local Group of galaxies are in Cassiopeia. NGC 185 is a magnitude 9.2 elliptical galaxy of type E0, 2 million light-years away. Slightly dimmer and more distant NGC 147 is a magnitude 9.3 elliptical galaxy, like NGC 185 it is an elliptical of type E0; it is 2.3 million light-years from Earth. Though they do not appear in Andromeda, both dwarf galaxies are gravitationally bound to the far larger Andromeda Galaxy.
===Pattern from Alpha Centauri===
If one were able to observe Earth's Sun from Alpha Centauri, the closest star to our solar system, it would appear in Cassiopeia as a yellow-white 0.5 magnitude star. The famous W of Cassiopeia would become a zig-zag pattern with the Sun at the leftmost end, closest to ε Cas.
===Meteor showers===
The December Phi Cassiopeiids are a recently discovered early December meteor shower that radiates from Cassiopeia. Phi Cassiopeiids are very slow, with an entry velocity of approximately 16.7 kilometers per second. The shower's parent body is a Jupiter family comet, though its specific identity is unknown.
==Mythology==
The constellation is named after Cassiopeia, the queen of Aethiopia. Cassiopeia was the wife of Cepheus, King of Aethiopia and mother of Princess Andromeda. Cepheus and Cassiopeia were placed next to each other among the stars, along with Andromeda. She was placed in the sky as a punishment for her boast that Andromeda was more beautiful than the Nereids; she was forced to wheel around the North Celestial Pole on her throne, spending half of her time clinging to it so she does not fall off.
Cassiopeia has been variously portrayed throughout her history as a constellation. In Persia, she was drawn by al-Sufi as a queen holding a staff with a crescent moon in her right hand, wearing a crown. In France, she was portrayed as having a marble throne and a palm leaf in her left hand, holding her robe in her right hand. This depiction is from Augustin Royer's 1679 atlas.
==In non-Western astronomy==
In Chinese astronomy, the stars forming the constellation Cassiopeia are found among three areas: 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).
The Chinese astronomers saw several figures in what is modern-day Cassiopeia. Kappa, Eta, and Mu Cassopeiae formed a constellation called the Bridge of the Kings; when seen along with Alpha and Beta Cassiopeiae, they formed the great chariot Wang-Liang. The charioteer's whip was represented by Gamma Cassiopeiae, sometimes called "Tsih", the Chinese word for "whip".
In the 1600s, various Biblical figures were depicted in the stars of Cassiopeia. These included Bathsheba, Solomon's mother; Deborah, an Old Testament prophet; and Mary Magdalene. a disciple of Jesus.
A figure called the "Tinted Hand" also appeared in the stars of Cassiopeia in some Arab atlases. This is variously said to represent a woman's hand dyed red with henna, as well as the bloodied hand of Muhammad's daughter Fatima. The hand is made up of the stars 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.
Another Arab constellation that incorporated the stars of Cassiopeia was the Camel. Its head was composed of Lambda, Kappa, Iota, and Phi Andromedae; its hump was Beta Cassiopeiae; its body was the rest of Cassiopeia, and the legs were composed of stars in Perseus and Andromeda.
Other cultures see a hand or moose antlers in the pattern. These include the Lapps, for whom the W of Cassiopeia forms an elk antler. The Chukchee of Siberia similarly saw the five main stars as five reindeer stags.
The people of the Marshall Islands saw Cassiopeia as part of a great porpoise constellation. The main stars of Cassiopeia make its tail, Andromeda and Triangulum form its body, and Aries makes its head. In Hawaii, Alpha, Beta, and Gamma Cassiopeiae were named. Alpha Cassiopeiae was called Poloahilani, Beta Cassiopeiae was called Polula, and Gamma Cassiopeiae was called Mulehu. The people of Pukapuka saw the figure of Cassiopeia as a distinct constellation called Na Taki-tolu-a-Mataliki.
== In popular culture ==
The Cuban artist Silvio Rodríguez wrote a song to Cassiopeia just after almost dying in a car crash.
Rock group Third Eye Blind mentions Cassiopeia in their song "Bonfire" and companion song "Lightning Comes, Goes".
Shabutie (now Coheed and Cambria) wrote a song called Cassiopeia on their "Penelope EP"
Also, the Korean group TVXQ's fanbase was named after this constellation because of the positioning of the letters TVfXQ on the keyboard (a variant of their group name) resembled that of the constellation. The official TVXQ Korean fanclub (Cassiopeia) was in the 2008 Guinness world records for largest official fanclub in the world.
The constellation features in the storyline of the 2001 film Serendipity.
The binary star that is the main star of the constellation, features as setting for at least a part of Charles Sheffield's 1985 Science Fiction novel, Between the Strokes of Night.
On Joanna Newsom's independent label debut album The Milk-Eyed Mender, released on March 23, 2004 on by Drag City, the eighth song is titled Cassiopeia. It runs 3:20min.
Consumer electronics company Casio used Cassiopeia as the name for a line of Pocket PCs running Microsoft's Windows CE in the late 90s.
The constellation is mentioned in the movie Spartan by Val Kilmer while pointing out North on a map.
It is mentioned in the movie Omen III: The Final Conflict (1981) as a sign of the second coming of Christ.
Cassiopeia is mentioned in the Broadway musical In the Heights during the song "Paciencia y Fe (Patience and Faith)".
Cassiopeia is the name of a song by the band Dragonland, on their album "Astronomy".
Cassiopeia is also the name of a champion in the multiplayer online battle arena game League of Legends.
Cassiopeia is the title of the first track on the album "Under the Silver of Machines (2007)" by the Alt Rock band Last Winter.
In the 1974 USSR movie Otroki vo vselennoy (Teens in the Universe), 7 teenage kids from Soviet Russia ( all Russians) crossed the interstellar space to land on the planet (orbiting Schedar, Alpha Cassiopeiae) to save its human population from enslaving robots.
In the French animated TV series Once Upon a Time... Space, the main antagonist is the military republic of Cassiopeé (Cassiopeia in French), whose symbol is the W formed by the brightest stars of that constellation.
In the original Super Sentai series, Himitsu Sentai Gorenger, Cassiopeia's cosmic rays are the weakness of the main antagonist, the Black Cross Führer, and the names of the Gorengers themselves (with the exception of a temporary replacement for one of them) begin with one of the kana for Cassiopeia.
In Harry Potter, Cassiopeia Black was a pure-blood witch, the eldest daughter of Cygnus Black II and Violetta Bulstrode and sister of Pollux Black, Marius Black and Dorea Black. Cassiopeia never married or had any children.
==In the news==
In May 2011, Israeli air traffic controllers dispatched two warplanes and two attack helicopters to investigate what they thought were suspicious lights in the sky. When observing the suspicious "enemy aircraft", the pilots confirmed that these were the stars of the Cassiopeia constellation.
==Namesakes==
USS Cassiopeia (AK-75) was a United States Navy Crater class cargo ship named after the constellation.
==See also==
*IC 10 – dwarf galaxy
*SN 1572 – Tycho's Star or Tycho's Supernova - B Cassiopeiae
*Cepheus XR-1 - radio source actually in Cass.
*Cassiopeia (Chinese astronomy)
==References==
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==External links==
* The Deep Photographic Guide to the Constellations: Cassiopeia
* The clickable Cassiopeia
* Star Tales – Cassiopeia
 
Category:Constellations
Category:Northern constellations
Category:Constellations listed by Ptolemy