As determined by the Hipparcos astrometry satellite,[15][16] this system is located at a distance of approximately 139 light-years (43 parsecs) from the Sun.

[2] Of the ten brightest stars in the night-time sky by apparent magnitude,[nb 1] Alpha Eridani is the hottest and bluest in color because it is spectral type B. Achernar has an unusually rapid rotational velocity, causing it to become oblate in shape.

[17] The system bears the traditional name of Achernar (sometimes spelled Achenar), derived from the Arabic آخر النهر ākhir an-nahr, meaning "The End of the River".

Consequently, Achernar itself is known as 水委一 (Shuǐ Wěi yī, English: the First Star of Crooked Running Water).

[22] USS Achernar (AKA-53) was a United States Navy attack cargo ship named after the star.

[23] Achernar is in the deep southern sky and never rises above the horizon north of 33°N, roughly the latitude of Dallas, Texas.

[10] Since it is actually a binary star, its highly distorted shape may cause non-negligible departures of the companion's orbital trajectory with respect to a Keplerian ellipse.

The entire star is surrounded by an extended envelope that can be detected by its excess infrared emission,[11] or by its polarization.

The projected separation of the two is slightly over one light year and they would not be gravitationally bound, but it is proposed that both are part of the Tucana-Horologium association.

[citation needed] The first star atlas to contain Achernar in the chart of Eridanus is Johann Bayer's Uranometria.

[30] Bayer did not observe it himself, and the first European knowledge of it is attributed to Pieter Dirkszoon Keyser on the first voyage of the Dutch to the East Indies ("Eerste Schipvaart").