Andromeda (constellation)

Andromeda is one of the oldest and most famous constellations in the night sky. It was first listed by the 2nd-century Greco-Roman astronomer Ptolemy and is still one of the 88 modern constellations used today. The constellation is named after Andromeda, a princess in Greek myth, who was saved by the hero Perseus.

Andromeda is best seen in the autumn evenings in the Northern Hemisphere. It is a large constellation, covering an area of 722 square degrees, which is over 1,400 times the size of the full moon. One of its brightest stars is Alpheratz, which sometimes is considered part of the neighboring constellation Pegasus. Another bright star, Mirach, appears reddish because it is a large, glowing red giant.

Perhaps the most famous feature of Andromeda is the Andromeda Galaxy (also called M31 or the Great Galaxy of Andromeda). This galaxy is the closest spiral galaxy to our own Milky Way and can even be seen with the naked eye on a dark night. Other interesting objects in Andromeda include smaller galaxies like M110 and M32, as well as the Blue Snowball Nebula, a beautiful planetary nebula that looks like a blue circle through a telescope.

History and mythology

The constellation Andromeda has deep roots in ancient stories, especially from Greek mythology. It is named after Andromeda, a princess from the tale. In the myth, Andromeda was chained to a rock as a punishment, but was saved by the hero Perseus. After her story, the goddess Athena placed her in the sky as a constellation.

Andromeda has been recognized as a constellation since ancient times. It was one of the 48 constellations listed by the Greek astronomer Ptolemy. Different cultures had their own names and stories for the stars in Andromeda. For example, in Chinese astronomy, stars from Andromeda were part of various constellations representing animals and buildings.

Features

Andromeda is a well-known constellation in the night sky. It contains many bright stars and interesting objects far away in space.

Stars

Further information: List of stars in Andromeda

Some important stars in Andromeda include:

• α And (Alpheratz), the brightest star, which once belonged to the constellation Pegasus.
• β And (Mirach), a red giant star with a planet orbiting it.
• γ And (Almach), a bright giant star that appears orange and is actually two stars orbiting each other.
• υ And (Titawin), a star system with four known planets.

Deep-sky objects

Andromeda is perhaps most famous for the Andromeda Galaxy (also called M31), a large galaxy visible to the naked eye. It is the closest large galaxy to our own Milky Way and may eventually collide with it in the far future.

The constellation also contains other interesting objects, such as:

• M32 and M110, two small galaxies that orbit the Andromeda Galaxy.
• NGC 891, a thin galaxy seen edge-on.
• NGC 752, a loose group of stars called an open cluster.

Meteor showers

Each November, the Andromedids meteor shower appears to come from Andromeda. Though usually weak, it produced spectacular displays in the past and had a notable outburst in 2011.