Aries

The Ram

GenitiveArietis
AbbreviationAri
Right Ascension1h44 to 3h27
Declination+10.2° to +30.9°
Area (sq deg)441
Brightest StarHamal
Optimum VisibilityNovember
Map of Aries

Derivation

Phrixus and Helle were the children of Athamas the King of Thebes. When their wicked step-mother threatened to have them killed, they escaped on a magical flying ram with a golden fleece. Helle was understandably alarmed by this experience, and fell from the ram into the sea, but her brother Phrixus survived and landed safely in Colchis. There, he sacrificed the ram to Zeus, who promptly placed it among the stars, while the King of Colchis kept its golden fleece.

Stars

Aries is one of the least conspicuous of the zodiacal constellations, and has only two stars above third magnitude. These are Hamal and Sheratan, the Alpha and Beta stars of the constellation. Unusually, these two stars not only appear to be close together in the sky, but actually are: they lie just six light years from one another.

The First Point of Aries

The First Point of Aries is a place of vital importance in the sky - here, the Ecliptic and the Celestial Equator cross, and when the Sun reaches this point, as it does once a year, the Vernal Equinox occurs. The First Point of Aries also marks the Celestial Meridian, which is the zero-point for calculations of Right Ascension.

Because of the effects of precession on the Earth, though, the First Point of Aries moves through the sky, and in fact it left the constellation from which it takes its name in about the year 70 BC, when it entered the neighbouring constellation of Pisces. Nonetheless, it retains the name 'First Point of Aries'. Roughly 23,000 years from now, the Sun will have completed its circuit of the zodiac, and the First Point will once again lie among the stars from which it takes its name.

Indexes

Related Entries