Constellations > Cassiopeia

Cassiopeia is a constellation located in the northern sky. The name was given in honor of the vain and boastful queen in the myths of Ancient Greece.

For the first time, the constellation Cassiopeia was recorded in the second century by Ptolemy with other constellations of the Perseus group (except for the Lizard). It is easy to recognize in the sky because it resembles a “W” in shape. It contains several notable objects: the open clusters Messier 52 and Messier 103, the Heart and Soul nebulae, the supernova remnants of Cassiopeia A, the star-forming cloud NGC 281 and the cluster NGC 7789 (White Rose).

Constellation cassiopeia

An objectDesignationMeaning of the nameObject typeMagnitude
1M52NoOpen star cluster5.00
2M103No Open star cluster7.40
3Shedar (Alpha Cassiopeia)“Breast”Orange giant2.24
4Kaph (Beta Cassiopeia)“Palm”Blue-white giant2.28
5Navi (Gamma Cassiopeia)“Ivan vice versa”Blue subdwarf2.47
6Rukbach (Cassiopeia Delta)“Knee”Double star2.68
7Seguin (Epsilon Cassiopeia)Origin unknownBlue-white giant3.37
eightAhird (This Cassiopeia)Origin unknownYellow and white dwarf3.44
nineZeta CassiopeiaNoBlue-white subgiant3.66
tenKappa CassiopeiaNoBlue-white supergiant4.16
elevenTheta Cassiopeia“Knee”Blue subgiant4.34
12Hi CassiopeiaNoYellow giant4.68
13Upsilon-2 Cassiopeia“The front of the garment”Yellow giant4.83

Facts, position and map

With an area of ​​598 square degrees, the constellation Cassiopeia is the 25th largest constellation. Located in the first quadrant of the northern hemisphere (NQ1). It can be found in latitudes: from + 90 ° to -20 °. Neighboring with Andromeda, Giraffe, Perseus, Lizard and Cepheus.

Lat. titleCassiopeia
(genus n. Cassiopeiae)
SymbolQueen on the throne
Right ascensionfrom 22h 52m until 3h 25m
Declinationfrom + 46 ° to + 77 °
Square598 sq. degrees
(25th place)
The brightest stars
(value <3m)
  • Shedar (α Cas) – 2.24m
  • Caf (β Cas) – 2.27m
  • Navi (γ Cas) – variable, 2.47m
  • Rukba (δ Cas) – 2.68m
Meteor showersNo
Nearby constellations
  • Giraffe
  • Cepheus
  • Lizard
  • Andromeda
  • Perseus
The constellation is visible in latitudes from + 90 ° to -13 °.
The best time to watch is September-November.

It contains three stars with planets and two Messier objects: M103 (NGC 581) and M52 (NGC 7654). The brightest star is Shedar. The Perseid meteor shower is associated with the constellation. Cassiopeia is part of the Perseus group along with Andromeda, Cepheus, Lizard, Pegasus, Perseus, Triangle, Whale and Charioteer. Consider the diagram of the constellation Cassiopeia on the map of the starry sky.

Constellation cassiopeia


Cassiopeia was the wife of the king of Ethiopia Cepheus (located next to her in the form of a constellation). She once boasted that she was superior in beauty to Nerid (50 sea nymphs created by the titan Nereus). They got angry and asked Poseidon to punish her. He could not refuse, as he was married to one of them (Amphitrite). He sent Cetus, a sea monster depicted in the constellation Cetus, who was to destroy the kingdom.

The king asked the oracle for help and he advised him to give Poseidon his daughter Andromeda. With great difficulty, they agreed and chained her to a rock. But at the last moment she was saved by Perseus, whom she later married. However, this is not the end. One of her fans, Phineus, came to the wedding and accused him of treason, since only he had the right to marry her. A battle took place in which Perseus used the head of Medusa the Gorgon. But, since many looked at her, the king and queen also became stone.

Poseidon sent Cassiopeia and Cepheus to heaven. But he still punished her, since for six months the constellation is wrapped upside down. Most often she is depicted sitting on a throne and combing her hair.

Main stars

Cassiopeia is distinguished by its unique “W” shape – an asterism created by five bright stars. From left to right: Epsilon, Delta, Gamma, Alpha and Beta Cassiopeia. Explore the bright stars of the constellation Cassiopeia with detailed descriptions and characteristics.

Shedar (Alpha Cassiopeia) is an orange giant of spectral type K0IIIa, about 228 light years distant. This is a suspicious variable star. The apparent magnitude can vary depending on which photometric system is used. The range contains from 2.20 to 2.23 values. Located in the lower right corner of the W-asterism. The name Shedar is taken from the Arabic “şadr” – “chest”. It marks the starry position – in the heart of Cassiopeia.

Kaph (Beta Cassiopeia) is a subgiant or giant of the spectral type F2 III-IV. Distance 54.5 light years from us. It is a Delta Shield type variable star. Only Altair (a star in the constellation Eagle and 12th in the sky) is brighter than her in this class. It is a yellow-white star 28 times brighter than the Sun and 4 times as large. It is now in the process of cooling and will one day become a red giant.

Variables of the Delta Shield type exhibit fluctuations in brightness due to radial and non-radial pulsations on the surface. These are usually giants or main sequence stars of spectral types ranging from A0 to F5.

The average apparent magnitude is 2.27. From Arabic, kaf is translated as “palm” (that is, the palm of the Pleiades is a well-known cluster in the constellation Taurus). Other traditional names are al-Sanam al-Naka and al-Kaff al-Hadib.

Along with the stars Alferaz (Andromeda) and Algenib (Pegasus), Kaph was perceived as one of the Three Guides – three bright stars that create an imaginary line from Kaf to Alferatz to the celestial equator (the point where the Sun passes at the spring and autumn equinox).

Navi (Gamma Cassiopeia) is an eruptive variable star that serves as the prototype for the variable stars Gamma Cassiopeia. Shows irregular changes in brightness from 2.20 to 3.40 magnitudes. It is the central W-shaped star and the brightest in the constellation (now).

It is a blue star (spectral type B0.5 IVe) located 610 light years away with a brightness 40,000 times that of the Sun and about 15 solar masses. Due to its rapid rotation, it expands at the equator and creates a “maternity” disk of lost mass and material.

It is a well-known X-ray source. The number is 10 times higher than that of other class B or Be stars. It is a spectroscopic binary star. A satellite with the mass of the Sun has a magnitude of 11 and a distance of two arc seconds. Rotates in 204 days.

The Chinese call it Tsikh – “whip”. She also has the nickname “Navi” inherited from the astronaut Virgil Grissom. Navi is Ivan (in English Ivan is the middle name of the astronaut), written in reverse order. The astronauts used the star as a reference point.

Rukbach (Delta Cassiopeia) is an eclipsing binary star with a period of 460 days. Belongs to spectral class A5. It is 99 light years distant and has an apparent magnitude between 2.68 and 2.74. It is the fourth brightest in the cluster. The name came from the Arabic – “knee”. She is sometimes called Xora.

Seguin (Epsilon Cassiopeia) is a bright blue and white B-class giant, 440 light years distant. 2500 times lighter than the Sun with an apparent magnitude of 3.34. Age – 65 million years. The star is at the end of a hydrogen fusion cycle. It has a very weak spectral absorption of helium.

Achird (Eta Cassiopeia) is a yellow-white G-type dwarf hydrogen star, slightly cooler than the Sun. The surface temperature is 5730 Kelvin, and the apparent magnitude is 3.45. It is the closest Cassiopeia star to our system (only 19.4 light years away).

Ahird has a companion, a class K orange dwarf with an apparent magnitude of 7.51, 11 arc seconds away. Both are classified as variable star RS Hounds. They form a close binary star and have active chromospheres that create large star spots. This leads to changes in luminosity – the brightness fluctuates by 0.05 magnitudes.

Zeta Cassiopeia is a blue-white subgiant (B2IV), 600 light years away. Visible visual magnitude 3.67. It is a variable star SPB (slowly pulsating B) with a magnetic field. The rotation speed is 56 km / s, and the period is 5.37 days.

Ro Cassiopeia is a yellow hypergiant (a rare type, since there are only 7 of them in the Milky Way). Belongs to spectral class G2Ia0e and is 11,650 light years distant. One of the brightest stars. Despite the distance, it can be viewed without technical equipment.

550,000 times brighter than the Sun with an absolute magnitude of -7.5. The apparent visual magnitude ranges from 4.1 to 6.2. This is a semi-regular variable with huge bursts every 50 years (because of this, brightness changes). In 2000-2001, the star ejected about 10,000 Earth masses in one flare.

Scientists believe it exploded like a supernova because it used up most of its nuclear fuel. But if this is so, then the light from the explosion has not yet reached us.

V509 Cassiopeia is a G-type supergiant, about 7,800 light years distant. The yellow-white star is a semi-regular variable. The luminosity varies within 4.75-5.5.

Celestial objects

Messier 52 (NGC 7654) is an open cluster 5,000 light years away. It has an apparent magnitude of 5.0, so it can be seen with binoculars.

Messier 52

Messier 52

It is 35 million years old and 13 arc minutes (19 light years) in diameter.

The cluster was found in 1774 by Charles Messier. Among the brightest stars, there are two yellow giants of magnitude 7.77 and 8.22.

Messier 103 (NGC 581) is an open cluster 10,000 light years away. Accommodates 172 stars. Age – 25 million years.

Messier 103

Messier 103

The cluster was discovered by the French astronomer Pierre Meschen in 1781. It is noteworthy that this turned out to be the last object that Charles Messier added to his catalog.

Cassiopeia A is a supernova remnant. It is the most powerful radio source in the sky outside the solar system and was one of the first radio sources discovered in 1947.

Cassiopeia A

Cassiopeia A

It is a cloud of material thrown out by the explosion. It is 10 light years in diameter and expands at a speed of 4000-6000 km / s. The temperature is 50 million degrees Fahrenheit.

The explosion occurred about 11,000 years from Earth. The first supernova light came to us only 300 years ago.

NGC 281 (Packman Nebula) is a large gas cloud that has recently undergone star formation. Contains a huge amount of ionized atomic hydrogen (H II). Illuminates young, hot, blue stars with ultraviolet light.

NGC 281

NGC 281

It is called the Packman Nebula because it resembles a popular video game character.

Distance 9500 light years from Earth. It was discovered in 1883 by the American astronomer E.E. Barnard.

NGC 7789 (White Rose) is an open star cluster 7,600 light years away. Apparent magnitude – 6.7. In 1783, it was found by the British astronomer Caroline Herschel.

The cluster is also called the White Rose or Carolina Rose because the star loops resemble rose petals.

NGC 185 (Caldwell 18) is a dwarf spheroidal galaxy 2.08 million light years away. It is a satellite of the Andromeda Nebula. Belongs to the Seyfert type with an active galactic nucleus. Contains young star clusters and demonstrates evidence of star formation.

It was discovered by John Herschel in 1787. The first photograph was due to James Keeler in 1898-1900. He used the Crossley Telescope (36 inches / 910 mm), a reflective telescope located at the Lick Observatory in California.

NGC 147 (Caldwell 17) is a dwarf spheroidal galaxy 2.53 million light-years from Earth. It is also a satellite of the Andromeda Nebula and is a member of the Local Group of Galaxies. Originally found in 1829 by John Herschel. Visible visual magnitude 10.5.

You have the opportunity to study the constellation Cassiopeia of the Northern Hemisphere more carefully if you use not only our photos and diagrams, but 3D models and a telescope online. For an independent search, a map of the starry sky is suitable.

Constellations of the autumn sky

SeptemberEagle Capricorn Swan Dolphin Small Horse Indian Microscope Peacock Arrow Chanterelle
OctoberAquarius Cepheus Crane Lizard Octant Pegasus Southern Fish
NovemberAndromeda Cassiopeia Phoenix Fish Sculptor Toucan

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