Cetus
Encyclopedia
Cetus is a constellation
. Its name refers to Cetus
, a sea monster
in Greek mythology
, although it is often called 'the whale
' today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius
, Pisces
, and Eridanus
.
, the ecliptic
passes close to its constellation boundary, and thus the planets may be seen in Cetus for brief periods of time. This is even more true of asteroids, since their orbits usually have a greater inclination
to the ecliptic than planets. For example, the asteroid
4 Vesta
was discovered in this constellation in 1807.
in Cetus is Mira
(or ο Ceti), the first variable star
to be discovered. Over a period of 331.65 days it can reach a maximum magnitude
as high as 2.0m, one of the brightest in the sky and easily visible to the unaided eye, then drop to 10.1m and back again. Its discovery in 1596 by David Fabricius
further dented the supposed unchangeability of the heavens and lent support to the Copernican revolution
.
Other stars in the constellation include α Ceti
(Menkar); β Ceti
(Deneb Kaitos), brightest in the constellation; and τ Ceti
, the 17th closest star to Earth.
, so that many distant galaxies
are visible, unobscured by dust from the Milky Way
. Of these, the brightest is Messier 77
(NGC 1068), a 9th magnitude spiral galaxy
near δ Ceti
. Recently, the galactic cluster JKCS 041
was confirmed to be the most distant cluster of galaxies yet discovered.
, the stars of Cetus are found among two areas: 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).
was a United States Navy
Crater class cargo ship
named after the constellation.
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
. Its name refers to Cetus
Cetus (mythology)
In ancient Greek, the word ketos - Latinized as cetus - denotes a large fish, a whale, a shark, or a sea monster. The sea monsters slain by Perseus and Heracles were each referred to as a cetus by ancient sources. The term cetacean originates from cetus. In Greek art, cetea were depicted as...
, a sea monster
Sea monster
Sea monsters are sea-dwelling mythical or legendary creatures, often believed to be of immense size.Marine monsters can take many forms, including sea dragons, sea serpents, or multi-armed beasts. They can be slimy or scaly and are often pictured threatening ships or spouting jets of water...
in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
, although it is often called 'the whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
' today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius
Aquarius (constellation)
Aquarius is a constellation of the zodiac, situated between Capricornus and Pisces. Its name is Latin for "water-bearer" or "cup-bearer", and its symbol is , a representation of water....
, Pisces
Pisces (constellation)
Pisces is a constellation of the zodiac. Its name is the Latin plural for fish, and its symbol is . It lies between Aquarius to the west and Aries to the east...
, and Eridanus
Eridanus (constellation)
Eridanus is a constellation. It is represented as a river; its name is the Ancient Greek name for the Po River. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is the sixth largest of the modern...
.
Ecliptic
Although Cetus is not considered part of the zodiacZodiac
In astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude which are centred upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year...
, the ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
passes close to its constellation boundary, and thus the planets may be seen in Cetus for brief periods of time. This is even more true of asteroids, since their orbits usually have a greater inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
to the ecliptic than planets. For example, the asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
4 Vesta
4 Vesta
Vesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta....
was discovered in this constellation in 1807.
Stars
The most notable starStar
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
in Cetus is Mira
Mira
Mira also known as Omicron Ceti , is a red giant star estimated 200-400 light years away in the constellation Cetus. Mira is a binary star, consisting of the red giant Mira A along with Mira B. Mira A is also an oscillating variable star and was the first non-supernova variable star discovered,...
(or ο Ceti), the first variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
to be discovered. Over a period of 331.65 days it can reach a maximum magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
as high as 2.0m, one of the brightest in the sky and easily visible to the unaided eye, then drop to 10.1m and back again. Its discovery in 1596 by David Fabricius
David Fabricius
David Fabricius , was a German theologian who made two major discoveries in the early days of telescopic astronomy, jointly with his eldest son, Johannes Fabricius ....
further dented the supposed unchangeability of the heavens and lent support to the Copernican revolution
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....
.
Other stars in the constellation include α Ceti
Alpha Ceti
Alpha Ceti is a star in the constellation of Cetus. It has the traditional name Menkar or Menkab. The name Menkar derives from the Arabic word منخر manħar "nostril" ....
(Menkar); β Ceti
Beta Ceti
Beta Ceti is the brightest star in the constellation Cetus. Although it has the Bayer designation "beta", it is actually brighter than Alpha Ceti. It has the traditional names Deneb Kaitos and Diphda...
(Deneb Kaitos), brightest in the constellation; and τ Ceti
Tau Ceti
Tau Ceti is a star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under 12 light-years from the Solar System, it is a relatively close star. Tau Ceti is metal-deficient and so is thought to be less likely to...
, the 17th closest star to Earth.
Deep sky objects
Cetus lies far from the galactic planeGalactic plane
The galactic plane is the plane in which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles...
, so that many distant galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
are visible, unobscured by dust from the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. Of these, the brightest is Messier 77
Messier 77
Messier 77 is a barred spiral galaxy about 47 million light-years away in the constellation Cetus. Messier 77 is an active galaxy with an Active Galactic Nucleus , which is obscured from view by astronomical dust at visible wavelengths...
(NGC 1068), a 9th magnitude spiral galaxy
Spiral galaxy
A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
near δ Ceti
Delta Ceti
Delta Ceti is a Class B2, fourth-magnitude star in the constellation Cetus.This star, along with α Cet , λ Cet , γ Cet , μ Cet, ξ1 Cet and ξ2 Cet were Al Kaff al Jidhmah, "the Part of a Hand".....
. Recently, the galactic cluster JKCS 041
JKCS 041
JKCS 041 is a group of galaxies with the distinction of being the farthest away group from Earth ever observed, as of 2009. It is estimated to be 10.2 billion light years away, seen at redshift 1.9. The cluster is located in the constellation Cetus at a photometrically determined redshift of z=1.9...
was confirmed to be the most distant cluster of galaxies yet discovered.
Equivalents
In Chinese astronomyChinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, the stars of Cetus are found among two areas: 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).
Namesakes
USS Cetus (AK-77)USS Cetus (AK-77)
The USS Cetus was a Crater-class cargo ship in the service of the United States Navy in World War II. Named after the equatorial constellation Cetus, it was the only ship of the Navy to bear this name....
was a United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
Crater class cargo ship
Crater class cargo ship
Crater-class cargo ship is a category of freighter that was constructed for use by the United States Navy during World War II under Maritime Commission EC2-S-C1 type....
named after the constellation.