Andromeda (constellation)

Andromeda is a constellation in the northern sky, named after the mythological princess Andromeda. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and remains one of the 88 modern constellations.

Andromeda is best viewed in the autumn months in the Northern Hemisphere. It is located near Perseus, Cassiopeia, and Pegasus. A key feature of Andromeda is its association with the Andromeda Galaxy (M31), the nearest large galaxy to the Milky Way. The Andromeda Galaxy is visible to the naked eye under dark sky conditions as a faint, hazy patch of light.

The brightest star in Andromeda is Alpheratz (α Andromedae), which, despite its designation, is actually part of the constellation Pegasus. The second brightest star is Mirach (β Andromedae), and the third brightest is Almaak (γ Andromedae).

In Greek mythology, Andromeda was the daughter of King Cepheus and Queen Cassiopeia of Aethiopia. Cassiopeia boasted that Andromeda was more beautiful than the Nereids, sea nymphs, which angered Poseidon. As punishment, Poseidon sent a sea monster, Cetus, to ravage Aethiopia. To appease Poseidon, Andromeda was chained to a rock as a sacrifice to Cetus. However, Perseus slew the monster and rescued Andromeda, later marrying her. After her death, she was placed among the stars.

Besides the Andromeda Galaxy, the constellation also contains several other deep-sky objects, including the elliptical galaxies M32 and M110, which are satellite galaxies of the Andromeda Galaxy.