Eridanus, the River, is an ancient constellation that winds from the foot of Orion deep into the southern sky, ending at the bright star Achernar.
At a glance
| stars in the figure | 30 |
|---|---|
| nearest star of the figure | Epsilon Eridani, 10.5 light-years (3.22 pc) |
| farthest star of the figure | Nu Eridani, 675 light-years (207 pc) |
| depth | the farthest is 64 × farther than the nearest |
Read off the piece’s own catalogue, the same values it draws with.
About Eridanus
Eridanus is one of the constellations catalogued by Ptolemy, a long, meandering river of mostly faint stars. In Greek myth it was the river into which Phaethon fell, struck down after he lost control of the chariot of the Sun. It is among the largest constellations, and it runs from Cursa, beside Rigel, south-west and then south until it reaches Achernar near the south celestial pole.
Achernar, the end of the river, is a hot blue star spinning so fast that it is strongly flattened at its poles. From Greece it never rose, and in Ptolemy’s day the river ended at Acamar instead. Along the way lie Zaurak, Rana, Azha, Beid and the chain of Tau stars, and some of the Sun’s nearest neighbours.
The best known of them is Epsilon Eridani, a young star a little smaller than the Sun, surrounded by belts of dust much like a younger Solar System. The northern reaches of the river are seen in the evening in northern winter; Achernar is visible only from the southern hemisphere and the tropics.
What you see in the piece
This is one of the deepest figures in the sky. With CONSTELLATIONS on, fly out: Epsilon Eridani is a close neighbour while Nu Eridani lies very much farther off, and the river breaks into stars strewn through a great volume of space.
Questions
How far away is Epsilon Eridani?
Epsilon Eridani, the nearest star of the figure, is 10.5 light-years (3.22 pc) from the Sun.
How deep is the figure of Eridanus?
Its farthest star, Nu Eridani, is 675 light-years (207 pc) away, 64 × farther than Epsilon Eridani.