Information: - A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union (IAU). The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names. - The Milky Way is the galaxy that contains our Solar System. The descriptive "milky" is derived from the appearance from Earth of the galaxy a band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term "Milky Way" is a translation of the Latin ', from the Greek (', "milky circle"). From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. - The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth. It is the nearest major galaxy to the Milky Way and was often referred to as the Great Andromeda Nebula in older texts. It received its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. - A Supercluster is a large group of smaller galaxy clusters or galaxy groups, which is among the largest-known structures of the cosmos. The Milky Way is part of the Local Group galaxy cluster (that contains more than 54 galaxies), which in turn is part of the Laniakea Supercluster. This supercluster spans over 500 million light-years, while the Local Group spans over 10 million light-years. The number of superclusters in the observable universe is estimated to be 10 million. - The International Astronomical Union (IAU UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the internationally recognized authority for assigning designations to celestial bodies (stars, planets, asteroids, etc.) and any surface features on them. - Peculiar motion or peculiar velocity refers to the true velocity of an object, relative to a rest frame. - The Virgocentric flow (VCF) is the preferred movement of Local Group galaxies towards the Virgo cluster caused by its overwhelming gravity, which separates bound objects from the Hubble flow of cosmic expansion. The VCF can refer to the Local Group's movement towards the Virgo "Super"cluster, since its center is considered synonymous with the Virgo cluster, but more tedious to ascertain due to its much larger volume. The excess velocity of Local Group galaxies towards, and with respect to, the Virgo Cluster are 100 to 400km/s. This excess velocity is referred to as each galaxy's peculiar velocity. - The Local Group is the galaxy group that includes the Milky Way. The Local Group comprises more than 54 galaxies, most of them dwarf galaxies. Its gravitational center is located somewhere between the Milky Way and the Andromeda Galaxy. The Local Group covers a diameter of (about 10 meters) and has a binary (dumbbell) distribution. The group itself is a part of the larger Virgo Supercluster, which in turn may be a part of the Laniakea Supercluster. - A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, the Milky Way, are invisible to the naked eye from Earth. Indeed, most are invisible from Earth even through the most powerful telescopes. - The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of galaxies that contains the Virgo Cluster in addition to the Local Group, which in turn contains the Milky Way and Andromeda Galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs (110 million light-years). It is one of about 10 million superclusters in the observable universe. - In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with Earth. All objects in the observer's sky can be thought of as projected upon the inside surface of the celestial sphere, as if it were the underside of a dome or a hemispherical screen. The celestial sphere is a practical tool for spherical astronomy, allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant. - The Virgo Cluster ( VC ) is a cluster of galaxies whose center is 53.8 0.3 Mly ( 16.5 0.1 Mpc ) away in the constellation Virgo . Comprising approximately 1300 ( and possibly up to 2000 ) member galaxies , the cluster forms the heart of the larger Virgo Supercluster , of which the Local Group ( LG ) is an outlying member . However , the LG experiences the mass of the VC Supercluster as the Virgocentric flow . It is estimated that the VC 's mass is 1.2 1015 M out to 8 degrees of the cluster 's center or a radius of about 2.2 Mpc . Many of the brighter galaxies in this cluster , including the giant elliptical galaxy Messier 87 , were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier 's catalogue of non-cometary fuzzy objects . Described by Messier as nebulae without stars , their true nature was not recognized until the 1920s . The cluster subtends a maximum arc of approximately 8 degrees centered in the constellation Virgo . Many of the member galaxies of the cluster are visible with a small telescope . Its brightest member is the elliptical galaxy Messier 49 ; however its most famous member is the also elliptical galaxy Messier 87 , that unlike the former is located in the center of the cluster . Given the information, choose the subject and object entities that have the relation of 'instance of'.
A:
virgo cluster , galaxy cluster