| ERIDANUS Chart | Midnight Culmination | Skylore | Description | Special Stars |

Constellation Data

  • Name: ERIDANUS
  • Translation: River
  • Abbreviation: Eri
  • Genitive: Eridani
  • Size: 6
  • Regions: Equatorial, Southern
  • Located Between: Hydrus, Doradus, Horologium, Fornax, Lepus, Orion
  • RA: 3 hours
  • Decl: -30 degrees
  • Season: Fall
  • Midnight Culmination: November 10
  • Pages where ERIDANUS is discussed in Chet Raymo's 365 Starry Nights: 217

What is the Genitive form?
What is Right Ascension (RA)?
Is this constellation ever visible from my latitude? What is Declination?

Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination?


The Nile to the Egyptians, the Po to Italians, and the Yellow River to the Chinese.

The ancient astronomer Hipparchos (ca. 150 B.C.) called Eridanus the "River of Orion."


The River Eridanus flows northward (like the Nile) from the bright star Achernar (Arabic for "End of the River") to Kursa (beta-Eridani) near Rigel in Orion. Eridanus is the longest (not largest) constellation, spanning over 50 degrees of declination, and its many faint stars glitter like reflecting light off the surface of its waves.

[star chart]

Star chart created with Voyager II Software for Macintosh, published by Carina Software. This is just a taste of what Voyager can do! For info on Voyager II software, call Carina Software at (510) 355-1266, write them at 12919 Alcosta Blvd Suite #7, San Ramon, CA 94583, or visit Carina Software's home page and check out Voyager II for yourself.

Special Stars

Achernar, alpha-Eridani, is the 10th brightest star, but is not visible from most of the United States. No brighter star than Achernar is closer to the south celestial pole, which lies midway between Achernar and Crux the Southern Cross. Distance: 85 LY. Apparent magnitude: 0.5. Declination: -57 degrees south.

Kursa (beta-Eridani). Distance: 100 LY. Apparent magnitude: 2.8. Declination: -05 degrees south (near Rigel).

Epsilon Eridani is one of two nearby stars that resemble the Sun. Perhaps it also is surrounded by planets! (The other is Tau Ceti in Cetus the Whale.) Distance: 10.7 LY. Apparent magnitude: 3.7. Declination: -10 degrees south.

Table of 25 Brightest Stars.
What is apparent stellar magnitude?

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