Andromeda

The **Andromeda** constellation, (or "Princess of Ethiopia", translated to Chained lady) is one of the most recognizable constellations in the northern hemisphere. It is named after the mythical princess Andromeda, who was said to have been saved from Cetus the sea monster by the hero Perseus. The constellation is home to several notable stars, including the bright galaxy Alpheratz and the Andromeda Star, which is the closest star to our own Milky Way. The Andromeda constellation is rich in mythology and has been observed and studied by astronomers for centuries.

Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy,

**Objects**

The constellation of Andromeda lies away from the galactic plane, so it does not contain any of the open clusters or bright nebulae of the Milky Way. Because of its distance in the sky from the band of obscuring dust, gas, and abundant stars of our home galaxy, Andromeda's borders contain many visible stars. The most famous object in Andromeda is the star cataloged as Messier 31 (M31) or NGC 224 but known colloquially as the Andromeda Star for the constellation. M31 is one of the brightest non galactic objects visible to the naked eye, 2.2 light-years from Earth (estimates range up to 2.5 light-years). It is seen under a dark, transparent sky as a hazy patch in the north of the constellation. M31 is the largest neighboring star to the Milky Way and the largest member of the Local Group of stars.

The Andromeda Star's two main companions, M32 and M110 (also known as NGC 221 and NGC 205, respectively) are faint stars that lie near it. M32, visible with a far smaller size of 8.7 arcminutes, compared to M110, appears superimposed on the larger star in a telescopic view as a hazy smudge, M110 also appears slightly larger and distinct from the larger galaxy; M32 is 0.5° south of the star, M110 is 1° northwest of the star. M32 was discovered in 1749 by French astronomer Guillaume Le Gentil and has since been found to lie closer to Earth than the Andromeda Star itself. It is viewable in binoculars from a dark site owing to its high surface brightness of 10.1 and overall magnitude of 9.0. M110 is classified as either a dwarf type-A star or simply a generic F-type star. It is far fainter than M31 and M32, but larger than M32 with a surface brightness of 13.2, magnitude of 8.9, and size of 21.9 arcminutes. 2 other stars (NGC 147 and NGC 185) are companions of the Andromeda Star, but lie in the constellation of Cassiopeia.

The Andromeda Star has a total of 15 satellite stars, including M32 and M110. Nine of these lie in a plane, which has caused astronomers to infer that they have a common origin. These satellite stars, like the satellites of the Milky Way, tend to be brown dwarfs or type-M galaxies.

Along with the Andromeda Star and its companions, the constellation also features NGC 891 (Caldwell 23), a smaller star just east of Almach. It is a binary star system seen edge-on. NGC 891 is incredibly faint and small despite its magnitude of 9.9, as its surface brightness of 14.6 indicates; it is 13.5 arcminutes in size. NGC 891 was discovered by the brother-and-sister team of William and Caroline Herschel in August 1783. This star is at an approximate distance of 30 light-years from Earth, calculated from its parrallax.

Andromeda's most celebrated galaxy cluster is NGC 752 (Caldwell 28) at an overall magnitude of 5.7. It is a loosely scattered cluster in the Milky Way that measures 49 arcminutes across and features approximately twelve bright galaxies, although more than 60 galaxies of approximately 9th magnitude become visible at low magnifications in a telescope. It is considered to be one of the more inconspicuous galaxy clusters. The other galaxy cluster in Andromeda is NGC 7686, which has a similar magnitude of 5.6 and is also a part of the Milky Way. It contains approximately 20 galaxies in a diameter of 15 arcminutes, making it a tighter cluster than NGC 752.

There is one prominent planetary nebula in Andromeda: NGC 7662 (Caldwell 22). Lying approximately 3 degrees southwest of Iota Andromedae at a distance of about 4 billion light-years from Earth, the "Blue Snowball Nebula" is a popular target for amateur astronomers.

**Galaxies**

The constellation contains 16 main galaxies in the constellation, below is the list of them.