|Right ascension||01 h 24 m 49 s to 05 h 11 m 13 s|
|declination||−57 ° 54 ′ 58 ″ to + 0 ° 24 ′ 13 ″|
|Completely visible||32.5 ° N to 89.5 ° S|
|Observation time for Central Europe||Winter (partially)|
|Number of stars brighter than 3 mag||4th|
|Brightest star (size)||Achernar (0.45)|
clockwise from north )
The northern part of the constellation Eridanus, the river as it can be seen with the naked eye in Central Europe
Eridanus is one of the largest constellations in the night sky. It extends as a chain of stars below Orion deep into the southern sky . The constellation is not very noticeable, as only four stars are brighter than the 3rd magnitude ; from Central Europe only the northern part is visible. The star Epsilon Eridani is 10.7 light years away and is one of the closest neighbors of the earthly sun .
In 2007 the Eridanus Supervoid was discovered in the constellation Eridanus , which is about one billion light years in size. In this region there are no stars, no galaxies , no black holes and no indications of dark matter .
In Greek mythology , the Eridanus was a river that sprang from the waters of Aquarius . A legend connects him with Phaeton , the son of the sun god Helios . When Phaeton took over his father's sky chariot one day, a disaster struck. The horse-drawn chariot that carried the sun got out of control. It got too close to the earth, burned northern Africa and darkened the skin of the people who lived there. The enraged Zeus killed Phaeton with a lightning strike. The constellation Eridanus was originally supposed to represent the path that the heavenly chariot took during this journey. Later the river into which the dead Phaeton fell was seen in it.
Originally the constellation already ended at the star Acamar (θ Eridani), the name is derived from the old Arabic and means "the end of the river". Because 2500 years ago Eridanus was due to the precession still 10 degrees south than today. Acamar appeared just above the horizon in Crete. The name of today's southernmost star, Achernar , also means "the end of the river", so it was probably extended by travelers from Asia Minor in late antiquity. Achernar was then at −71 ° declination and could not be observed even in Egypt.
Pieter Dirkszoon Keyser , who in 1595/96 had defined twelve “new” constellations during his southern voyage, on which he died, which his commander brought with him, renamed him to the Nile (“Het Zuyder eynde van den Nyli”), presumably as one of them four paradise rivers , in the tradition of Eratosthenes , who interpreted the Eridanus as the Egyptian river (although Hesiod already dealt with the two separately). As such it can also be found in Plancius and the sky maps printed by Jodocus Hondius , and in 1602/03 also in Willem Janszoon Blaeu . However, Johann Bayer lists him as Eridanus in the Ptolemaic tradition, and the alternative name never caught on.
|B.||F.||Names or other designations||Size (mag)||Lj||Spectral class|
|β||67||Cursa , Kursa, Dhalim||2.78||90||B3 V|
|γ||34||Zaurak , Zaurac||2.95||150||M0 III|
|θ||Acamar||3.0||163||A4 + A1|
|υ 4||41||3.55||120||B8 V|
|τ 4||16||3.69||250||M3.5 III|
|ε||18th||Epsilon Eridani||3.73||10.5||K2 V|
|υ 2||52||Beemin, Theemin||3.82||200||G9 III|
|ν 3||43||3.97||250||K5 III|
|ο 1||38||Both||4.04||200||F2 III|
|τ 3||11||4.09||80||A3 IV|
|τ 6||27||4.23||60||F3 III|
|τ 5||19th||4.27||300||B8 V|
|ο 2||40||Keid||4.43||16||K1 + A2|
|τ 1||1||4.47||50||F6 V|
|32||4.5||250||G8 + A2|
|τ 9||36||4.66||B6 V + B9.5V|
|τ 8||33||4.65||B6 V|
|τ 2||2||Angetenar , Al Anchat||4.75||182||K0 III|
|39||4.87||300||K3 + G2|
Achernar, the brightest star, is 144 light years away. It has a strange shape. Observations indicate that its diameter at the equator is 50% larger than at the poles. This flattening is attributed to a high rotational speed.
|θ||3.3 / 4.4||8.2 "|
|ο 2||4.5 / 9.7 / 10.8||83 "|
|32||4.8 / 6.1||6.8 "|
|f||4.8 / 5.4||8.1 "|
|39||4.9 / 8.0||6.4 "|
|p||5.8 / 5.9||11.5 "|
ο 2 Eridani is a triple system 15.9 light years away. The main star is about the size of our sun . One of the components is a white dwarf star that is only twice the diameter of the earth. This star is the easiest white dwarf to observe; it is already visible in an amateur telescope. The third component, a red dwarf star, can also be seen in a larger telescope.
|T Eri||7.4-13.2||252 days||Mira star|
T Eridani is a pulsation-variable star of the Mira type . At its maximum, it achieves an apparent brightness of 7.4 mag, so that it can be observed in bright prism binoculars or a smaller telescope. At the minimum, its apparent brightness drops to 13.2 mag. To find it, you need a larger telescope.
NGC 1132 is a rare giant elliptical galaxy 318 million light years away.
- Lexicon entry "Eridanus" , brockhaus.de
- Spiegel Online from August 24, 2007: A mysterious emptiness: Researchers discover a giant hole in the universe
- Gerd Graßhoff: The History of Ptolemy's Star Catalog . Springer Science & Business Media, 2013, ISBN 978-1-4612-4468-4 , p. 36 ( limited preview in Google Book search).
- Gerhard Fasching: Constellation studies sky maps, celestial bodies, constellations . Springer-Verlag, 2013, ISBN 978-3-322-86264-8 , pp. 112 ( limited preview in Google Book search).
- Paul Kunitzsch: Arabic star names in Europe . Otto Harrassowitz Verlag, 1959, ISBN 978-3-447-00549-4 , p. 99 ( limited preview in Google Book search).
- F. Verbunt, RH van Gent: Early star catalogs of the southern sky. In: Astronomy & Astrophysics. 530, 2011, p. A93, doi : 10.1051 / 0004-6361 / 201116795 .
- Obsolete Constellation , Ridpath, Startales.
- Michael Odenwald: The cosmic loner. In: FOCUS Online. Retrieved June 4, 2016 .