Andromeda GalaxyBarred spiral galaxy in the Local GroupThe Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a D25 isophotal diameter of about 46.56 kiloparsecs (152,000 light-years) and is approximately 765 kpc (2.5 million light-years) from Earth.
Local GroupThe Local Group is the galaxy group that includes the Milky Way, where Earth is located. It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellite galaxies form one lobe, and the Andromeda Galaxy and its satellite galaxies constitute the other.
Dwarf spheroidal galaxyA dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population. They are found in the Local Group as companions to the Milky Way and as systems that are companions to the Andromeda Galaxy (M31).
Andromeda (constellation)Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus.
Globular clusterA globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. This contrasts with open clusters, where the stars are only loosely bound and more easily disrupted.
Satellite galaxyA satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents are bound to their host galaxy, in the same way that planets within the Solar System are gravitationally bound to the Sun. While most satellite galaxies are dwarf galaxies, satellite galaxies of large galaxy clusters can be much more massive.
Sidney van den BerghSidney Van den Bergh (born 20 May 1929) is a retired Dutch-Canadian astronomer. Van den Bergh showed an interest in science from an early age, learning to read with books on astronomy. In addition to being interested in astronomy, he also liked geology and archeology. His parents got him science books, a telescope, and a microscope, although they wished him to pursue a more practical career and only follow astronomy as a hobby.
Light-yearA light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly 9460730472580.8 km, which is approximately 9.46 trillion kilometres or 5.88 trillion miles. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Despite its inclusion of the word "year", the term is a unit of distance, not a unit of time.
Milky WayGalaxy containing the Solar SystemArtist's impression of the structure of the Milky Way based on data from the European Space Agency's Gaia telescope, including the location of the spiral arms, bar, and bulgeThe Milky Way or Milky Way Galaxy, or simply the Galaxy, is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye.
ConstellationA constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellations were likely defined in prehistory. People used them to relate stories of their beliefs, experiences, creation, and mythology.
ParsecThe parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (au), i.e., 30.9 trillionkilometres (19.2 trillion miles). The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond (1/3600 of a degree).
Wide Field and Planetary Camera 2The Wide Field and Planetary Camera 2 (WFPC2) is a camera formerly installed on the Hubble Space Telescope. The camera was built by the Jet Propulsion Laboratory and is roughly the size of a baby grand piano. It was installed by servicing mission 1 (STS-61) in 1993, replacing the telescope's original Wide Field and Planetary Camera (WF/PC).*As an Amazon Associate I earn from qualifying purchases.