Generalities: it is an extremely wide southern constellation. It occupies about 2/3 in length (declination) of the southern sky. It transits at midnight at the end of November.

Origins and mythology: Eridanus represents the river Po (northern Italy). Young Fetonte fell in it when he got from his father Helium the permission to drive the wagon of the Sun. When he lost the control of it Jupiter was forced to demolish him with a lightning. Because of the form of this constellation, also the ancient Egyptians identified it with a river, obviously the Nile.

Stars: Eridanus shows a star of the first magnitude, Achernar, of magnitude 0.46,  white-blue color,  85 light-years far, ninth star of the whole sky for brightness. Besides Achernar there are other three stars under  magnitude 3 and other 11 under  magnitude 4. The three brightest stars after Achernar are beta (Kursa), gamma (Zaurak) and theta (Acamar).

Table of stars brighter than magnitude 3.5
 

Star	Proper name	Magnitude	Spectrum	Colour	Distance (light-years)	Notes
Alpha	Achernar	0.46	B5	white-blue	85
Beta	Kursa	2.79	A3	white	91
Theta	Acamar	2.92	A3+A2	white	55	Visual double star
Gamma	Zaurak	2.95	M0	red	143

Other objects: a planetary nebula and some weak galaxies are present.

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