| Constellation | |
List of stars in Eridanus |
|
| Abbreviation | Eri |
|---|---|
| Genitive | Eridani |
| Pronunciation | /ɨˈrɪdənəs/ Erídanus, genitive /ɨˈrɪdənaɪ/ |
| Symbolism | the river Eridanus |
| Right ascension | 3.25 h |
| Declination | −29° |
| Quadrant | SQ1 |
| Area | 1138 sq. deg. (6th) |
| Main stars | 24 |
| Bayer/Flamsteed stars |
87 |
| Stars with planets | 8 |
| Stars brighter than 3.00m | 4 |
| Stars within 10.00 pc (32.62 ly) | 13 |
| Brightest star | Achernar (α Eri) (0.46m) |
| Nearest star | ε Eri (10.50 ly, 3.22 pc) |
| Messier objects | None |
| Meteor showers | None |
| Bordering constellations |
Cetus Fornax Phoenix Hydrus Tucana (corner) Horologium Caelum Lepus Orion Taurus |
| Visible at latitudes between +32° and −90°. Best visible at 21:00 (9 p.m.) during the month of December. |
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Eridanus (pronounced /ɨˈrɪdənəs/) 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 constellations.
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At its southern end is the first magnitude star Achernar (α Eri). Achernar is a very peculiar star because it is one of the flattest stars known. Observations indicate that its radius is about 50% larger at the equator than at the poles. This distortion occurs because the star is spinning extremely rapidly.
Another well-known star in Eridanus is Epsilon Eridani, which has been popular in science fiction because it is relatively close and sun-like (see Epsilon Eridani in fiction). It is now suspected to have at least one extrasolar planet, which is thought to be a gas giant, like Jupiter.
The Eridanus Supervoid is the largest supervoid (an area of the universe devoid of galaxies) discovered as of 2007[update]. At a diameter of about one billion light years it is much larger than any other known void and represents a challenge for current theories of the origins of the universe to explain. It was discovered by linking a "cold spot" in the cosmic microwave background to an absence of radio galaxies in data of the US National Radio Astronomy Observatory's Very Large Array Sky Survey.[1] There is some speculation that the void may be due to quantum entanglement between our universe and another.[2][3][4]
Eridanus contains the galaxies NGC 1234 and NGC 1300, a grand design barred spiral galaxy.
The name Eridanus refers to the Po River, the main river of northern Italy. Its association with a river comes from the way its stars trace a tortuous path. In some star maps, Eridanus is depicted as a river flowing from the waters poured by Aquarius. In such maps, Aquarius is visualized as facing Eridanus, requiring a different perspective and a redesign of how the stars of Aquarius connect, so the water pours onto the same side as Eridanus.
According to one theory, the Greek constellation takes its name from the Babylonian constellation known as the Star of Eridu (MUL.NUN.KI). Eridu was an ancient city in the extreme south of Babylonia; situated in the marshy regions it was held sacred to the god Enki-Ea who ruled the cosmic domain of the Abyss - a mythical conception of the fresh-water reservoir below the Earth's surface.[5]
Eridanus is connected to the myth of Phaëton, who took over the reins of his father Helios' sky chariot (i.e., the Sun), but didn't have the strength to control it and so veered wildly in different directions, scorching both earth and heaven. Zeus intervened by striking Phaëton dead with a thunderbolt and casting him to earth. The constellation was supposed to be the path Phaëton drove along; in later times, it was considered a path of souls. Since Eridanos was also a Greek name for the Po (Latin Padus), in which the burning body of Phaëton is said by Ovid to have extinguished, the mythic geography of the celestial and earthly Eridanus is complex.[6]
The stars that correspond to Eridanus are also depicted as a river in Indian astronomy. Eridanus is called Srotaswini in Sanskrit, srótas meaning the course of a river or stream. Specifically, it is depicted as the Ganges on the head of Dakshinamoorthy, a Hindu incarnation of Siva. Dakshinamoorthy himself is represented by the constellation Orion.
The stars that correspond to Eridanus cannot be fully seen from China. In [[Chinese astronomy, the northern part is located within the White Tiger of the West (西方白虎, Xī Fāng Bái Hǔ). The unseen southern part was classified among the Southern Asterisms (近南極星區, Jìnnánjíxīngōu) by Xu Guangqi, based on knowledge of western star charts.
In some maps of the Star Trek universe the planet Vulcan is shown to be located at 40 Eridani A.[7]
The character Eridan Ampora's name in Andrew Hussie's comic MS Paint Adventures Homestuck was based off of the name Eridanus, which is his associated Zodiac sign in Aquarius.
Eridanus is also a system of planets in the Halo franchise, seen primarily in the novels and comics.
USS Eridanus (AK-92) was a United States Navy Crater class cargo ship named after the constellation.
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