Eridanus - The River

Learn about the constellation Eridanus - The River, location, facts, mythology, meteor showers and deep space objects.

Eridanus is a mythical river associated with Phaëton, and is the sixth largest of the 88 modern constellations. It was also one of Ptolemy's 48 constellations.

Location: Northern Winter 3h RA -29° Dec

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 ε 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, which is thought to be a gas giant, like Jupiter.

Eridanus Mythology

Eridanus is associated with two Greek myths, both likely to be derived from the shape of the constellation — that of a very twisty path. Eridanus was sometimes considered to be a river which flowed from the waters of Aquarius. Eridanus was more usually connected to the myth of Phaeton, who took over the reins of Helios' sky chariot, but didn't have the strength to control it, and so veered wildly in different directions. The result was that sometimes the chariot got too close to the Earth, creating a desert and burning people's skin (a myth they considered to explain the skin of the Ethiopians).

Eridanus Deep Space Objects

NGC 1535 is a small blue-grey planetary nebula visible in small amateur telescopes.