AchernarEridanus
looking toward
SSW191°
ALT 27° · FOV 93°
🌟ByulGil
observatory
Seoul
37°33′N · 126°58′E
2026.10.22 19:06
LIVE · 24 OF 40 ABOVE
Tonight's Sky
40 CONSTELLATIONS
constellation

Eridanus

에리다누스자리
The river of the sky · The River
Winter · hard to observe in May
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Science
The science

Eridanus is the "river of the sky" that begins near Rigel, Orion's bright foot-star, and flows long and winding down below the southern horizon. It is the sixth-largest constellation in the sky, and its chief star Achernar (meaning "the end of the river"), at the river's end (its southern mouth), is the ninth-brightest star in the night sky. This star spins so wildly fast that its equator bulges enormously, making it famous as the most flattened "rugby ball" of a star in the sky. Its southern end lies at such low declination, however, that from Korea only the river's upper reaches can be seen.

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Mythology
The myth

Eridanus is said to be the river into which Phaethon, son of the sun god Helios, fell to his death. Phaethon begged his father to let him drive the chariot of the Sun for just one day, but he could not master the fierce sky-horses and, straying from the heavenly path, ran wild. As the chariot dipped too close to the ground, the earth caught fire and deserts were born; seeing this, Zeus struck the chariot with a thunderbolt to save the world. Wrapped in flames, Phaethon fell from the sky and drowned in the waters of the Eridanus, and this river that mourned him rose into the sky to become a constellation.

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Stars
Main stars (equatorial)
CursaRA 5.13h · Dec -5.1° · m2.8
ZaurakRA 3.97h · Dec -13.5° · m3.0
RanaRA 3.72h · Dec -9.8° · m3.5
EpsilonRA 3.55h · Dec -9.5° · m3.7
AcamarRA 2.97h · Dec -40.3° · m2.9
AchernarRA 1.63h · Dec -57.2° · m0.5
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