Andromeda (constellation) in the context of "Northern celestial hemisphere"

In Greek mythology, Andromeda (/ænˈdrɒmɪdə/; Ancient Greek: Ἀνδρομέδα, romanized: Androméda or Ἀνδρομέδη, Andromédē) is the daughter of Cepheus, the king of Aethiopia, and his wife, Cassiopeia. When Cassiopeia boasts that she (or Andromeda) is more beautiful than the Nereids, Poseidon sends the sea monster Cetus to ravage the coast of Aethiopia as divine punishment. Queen Cassiopeia understands that chaining Andromeda to a rock as a human sacrifice is what will appease Poseidon. Perseus finds her as he is coming back from his quest to decapitate Medusa, and brings her back to Greece to marry her and let her reign as his queen. With the head of Medusa, Perseus petrifies Cetus to stop it from terrorizing the coast any longer.

As a subject, Andromeda has been popular in art since classical antiquity; rescued by a Greek hero, Andromeda's narration is considered the forerunner to the "princess and dragon" motif. From the Renaissance, interest revived in the original story, typically as derived from Ovid's Metamorphoses. The story has appeared many times in such diverse media as plays, poetry, novels, operas, classical and popular music, film, and paintings. A significant part of the northern sky contains several constellations named after the story's figures; in particular, the constellation Andromeda is named after her.

Perseus is a constellation in the northern sky, named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.

The galactic plane of the Milky Way passes through Perseus, whose brightest star is the yellow-white supergiant Alpha Persei (also called Mirfak), which shines at magnitude 1.79. It and many of the surrounding stars are members of an open cluster known as the Alpha Persei Cluster. The best-known star, however, is Algol (Beta Persei), linked with ominous legends because of its variability, which is noticeable to the naked eye. Rather than being an intrinsically variable star, it is an eclipsing binary. Other notable star systems in Perseus include X Persei, a binary system containing a neutron star, and GK Persei, a nova that peaked at magnitude 0.2 in 1901. The Double Cluster, comprising two open clusters quite near each other in the sky, was known to the ancient Chinese. The constellation gives its name to the Perseus Cluster (Abell 426), a massive galaxy cluster located 250 million light-years from Earth. It hosts the radiant of the annual Perseids meteor shower—one of the most prominent meteor showers in the sky.

De astronomia (Latin: [deː äs̠t̪rɔˈnɔmiä]; Concerning Astronomy) is a book of stories written in Latin, probably during the reign of Augustus (c. 27 BC – AD 14). Attributed to "Hyginus", the book's true author has been long debated. However, the art historian Kristen Lippincott argues that the author was likely Gaius Julius Hyginus, who served as the superintendent of the Palatine library under Caesar Augustus.

The text describes 47 of the 48 Ptolemaic constellations, centering primarily on the Greek and Roman mythology surrounding the constellations, though there is some discussion of the relative positions of stars. The stories it contains are chiefly based on Catasterismi, a work that was traditionally attributed to Eratosthenes.

NGC 169 is an unbarred spiral galaxy located in the constellation Andromeda. It was discovered on September 18, 1857, by R. J. Mitchell.

NGC 169 has a smaller companion named NGC 169A, also designated IC1559. The two are currently interacting, and the pair is included in Halton Arp's Atlas of Peculiar Galaxies.

Alpheratz is a prominent star system in the constellation of Andromeda. Pronounced /ælˈfɪəræts/, it has the Bayer designation Alpha Andromedae, Latinised from α Andromedae, and abbreviated Alpha And or α And, respectively. Alpheratz is the brightest star in the constellation when Mirach (β Andromedae) undergoes its periodical dimming. Immediately northeast of the constellation of Pegasus, it is the upper left star of the Great Square of Pegasus. It is located at a distance of 97 light-years from Earth.

Although it appears to the naked eye as a single star with overall apparent visual magnitude +2.06, it is actually a binary system composed of two stars in close orbit. The chemical composition of the brighter of the two stars is unusual as it is a mercury-manganese star whose atmosphere contains abnormally high abundances of mercury, manganese, and other elements, including gallium and xenon. It is the brightest mercury-manganese star known.

Gamma Andromedae is a multiple star system in the northern constellation of Andromeda. It is the third-brightest star in the constellation, after Alpheratz and Mirach. Its identifier is a Bayer designation that is Latinized from γ Andromedae, and is abbreviated Gam And or γ And, respectively. The system has the proper name Almach, pronounced /ˈælmæk/. Based on parallax measurements, it is estimated to be about 390 light-years distant. The system is drifting closer to the Sun with a radial velocity of −11.7 km/s.

Mirach is a prominent star in the northern constellation of Andromeda. It is pronounced /ˈmaɪræk/ and has the Bayer designation Beta Andromedae, which is Latinized from β Andromedae. This star is positioned northeast of the Great Square of Pegasus and is potentially visible to all observers north of latitude 54° S. It is commonly used by stargazers to find the Andromeda Galaxy. The galaxy NGC 404, also known as Mirach's Ghost, is seven arcminutes away from Mirach.

This star has an apparent visual magnitude of around 2.07, varying between 2.01 and 2.10, which at times makes it the brightest star in the constellation. Based upon parallax measurements, it is roughly 197 light-years (60 parsecs) from the Solar System. Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight. The star has a negligible radial velocity of 0.1 km/s, but with a relatively large proper motion, traversing the celestial sphere at an angular rate of 0.208″·yr.