Profile / Characteristics
| English translation | Latin declination and pronunciations | Size/ °² | # stars (visible) |
| the River | Eridanus – ih-RID-un-us Eridani – ih-RID-un-eye | 1138 | 199 |
Main Star (brightest one):
| Designation | HIP number | name in IAU-CSN | brightness |
| α Eri | HIP 7588 | Achernar | 0.46 mag (V) |
Our (modern) Explanation
The northern part of the constellation Eridanus was cataloged by the second-century astronomer Ptolemy, for him only named “The River”. “ Due to a mistake of Ptolemy who states that the brightest star of the constellation is at the end of the river, Dutch navigators in the 1590s extended the constellation further south when they sailed to the southern hemisphere and saw the bright star that is now called Achernar. This star and some others of our constellation Eridanus were invisible for the ancients and not listed in Ptolemy. In ancient times, scholars not only argued which one of the many rivers would be depicted here but also whether its waters flow northwards or southwards, so it is uncertain whether they had considered the “end of the river” close to Orion or close to the horizon. Ptolemy saw it in theta Eridani.
Ancient Globes
Farnese Globe
Kugel Globe
Mainz Globe
Ancient Lore & Meaning
Aratus
Reference:
English translation by Douglas Kidd (1997).
Aratus: Phaenomena, Cambridge Classical Texts and Commentaries, Series Number 34
Pseudo-Eratosthenes
References:
French translation by:
Jordi Pàmias i Massana and Arnaud Zucker (2013). Ératosthènes de Cyrène – Catastérismes, Les Belles Lettres, Paris
English version in:
Robin Hard (2015): Eratosthenes and Hyginus Constellation Myths with Aratus’s Phaenomena, Oxford World’s Classics
Early Modern Interpretation
Contemporary
As one of their first tasks in the 1920s, the newly founded International Astronomical Union (IAU) established constellation standards. The Belgian astronomer Eugène Delporte was assigned to the task to define borders of constellations parallel to lines of declination and right ascension. They were accepted by the General Assembly in 1928. The standardized names and abbreviations had already been accepted in 1922 and 1925.
