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Achernar
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Also called:
Alpha Eridani
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Achernar

star
Also known as: Alpha Eridani
Written by
Erik Gregersen
Erik Gregersen is a senior editor at Encyclopaedia Britannica, specializing in the physical sciences and technology. Before joining Britannica in 2007, he worked at the University of Chicago Press on the...
Erik Gregersen
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Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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History

Achernar, brightest star in the constellation Eridanus and the ninth brightest star in the sky. Achernar (Arabic for “end of the river”) is 144 light-years from Earth. It is a binary star with a B-type star, Achernar A, as its primary and a much fainter A-type star, Achernar B, orbiting the primary at a distance of 6.7 astronomical units (1 billion km, or 621 million miles) with a period of about 15 years. Achernar A rotates at a speed of more than 250 km (150 miles) per second and thus is flattened with its equatorial diameter 40 percent larger than its polar diameter.

(List of Brightest Stars as Seen from Earth)

Erik Gregersen
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