Eridanus (constellation) Guide, Meaning , Facts, Information and Description
| Eridanus | |
| Abbreviation | Eri |
| Genitive | Eridani |
| Meaning in English | the river |
| Right ascension | 1h 20m - 5h 10m |
| Declination | −58° - 0°
|
| Number of stars with apparent magnitude < 3 | 4 |
| Brightest star - Apparent magnitude | Achernar (α Eri) 0.46m
|
Eridanus (the river) is the sixth largest of the 88 modern constellations. It was also one of Ptolemy's 48 constellations.
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. Responsible for this is the fact that Achernar is spinning extremely fast.
Another well-known star in Eridanus is Epsilon Eridani, which has been popular in science fiction because it is relatively close and relatively sun-like. It is now known to have at least one planet (see Extrasolar planet).