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Eridanus

The River

Abbreviation:Eri
Genitive:Eridani
Origin:[antiquity]
Fully Visible:89°S – 32°N

One Greek myth associates this river with the path followed by Phaëton when he attempted to drive his father Helios' sky chariot. Phaëton couldn't control the chariot and it veered wildly in all directions, scorching heaven and earth. Zeus, king of the gods, struck Phaëton dead with a thunderbolt. Phaëton fell to earth and his body landed in the Po River, which is called Eridanos in ancient Greek.

This is one of the largest of the modern constellations and is the 'tallest', spanning nearly 60° in declination. A number of obsolete constellations have borrowed stars from it in the past, including Psalterium Georgii and Sceptrum Brandenburgicum (see below).

The constellation of Eridanus

Notable Features

Visible Named Stars
α Eri Achernar The brightest star in the constellation is actually first magnitude.
β Eri Cursa The name of this star means 'footstool' and reflects its position near the foot of Orion.
γ Eri Zaurak This third-magnitude star is the standard for the spectral class M0Ⅲ-Ⅲb.
δ Eri Rana The origin of the name of this high-proper-motion star is uncertain.
ε Eri Ran This is one of the closest stars to the Sun and one of the few nearby stars that is visible to the naked eye. It is known to have at least one exoplanet.
ζ Eri Zibal The name applies to the brighter component of this binary star.
η Eri Azha This K-type giant star exhibits high proper motion.
θ¹ Eri Acamar Acamar appears as a binary star through a telescope. It sometimes appears as Dalim (from the Arabic al‑ẓalīmān meaning 'the two male ostriches') in older star atlases and catalogues.
ο¹ Eri Beid For Arabic astronomers, this part of the sky was inhabited by ostriches. 'Beid' means 'the eggs'.
ο² Eri Keid A telescope reveals that Keid is a multiple star system.
τ² Eri Angetenar This star is aptly named as it marks 'the bend in the river'.
υ² Eri Theemin The name of this star also means 'the bend in the river'.
υ³ Eri Beemim As does this one!
53 Eri Sceptrum The name of this star is taken from the name of the obsolete constellation Sceptrum Brandenburgicum of which it was the brightest member.
Other Interesting Stars
CD−23 1056 Koeia This tenth-magnitude star is known to have at least one exoplanet. It is located just south of Angetenar (τ² Eri).
CD−30 1812 Montuno Located halfway between τ7 Eri and g Eri, this tenth-magnitude star is known to have at least one exoplanet.
HD 18742 Ayeyarwady This eighth-magnitude star is known to have at least one exoplanet and is found north of the star τ³ Eri.
HD 30856 Mouhoun This eighth-magnitude star is known to have at least one exoplanet. It is located near the border with Lepus.
WASP‑22 Tojil This twelfth-magnitude star is known to have at least one exoplanet and is lurking just south of τ5 Eri.
WASP‑50 Chaophraya Found near Azha (η Eri), this twelfth-magnitude star is known to have at least one exoplanet.
Meteor Shower Radiants
191 ERI η Eridanids There are no major meteor showers associated with this constellation. This minor shower is active from late July to mid-August, peaking around 8 August. It may be associated with the comet C/1852 K1 Chacornac.