query: instance_of ngc 8
supports: Earth, otherwise known as the world, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets. Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets; while the phenomena include supernovae explosions, gamma ray bursts, and cosmic microwave background radiation. More generally, all astronomical phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole. 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. Karl Hermann Struve (October 3, 1854  August 12, 1920) was a Russian astronomer. In Russian, his name is sometimes given as "German Ottovich Struve" (  ) or "German Ottonovich Struve" (  ). The Struve family (pronounced in German, in Russian) were a dynasty of five generations of astronomers from the 18th to 20th centuries. Members of the family were also prominent in chemistry, government and diplomacy. Gustav Wilhelm Ludwig Struve (November 1, 1858  November 4, 1920) was a Russian astronomer, part of the famous Baltic German Struve family. In Russian, his name is sometimes given as Lyudvig Ottovich Struve (  ) or Lyudvig Ottonovich Struve (  ). A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s, by using glass lenses. They found use in both terrestrial applications and astronomy.  NGC 8 is a double star system ( K5 and F8 ) in the constellation Pegasus , discovered on 29 September 1865 by Otto Struve . It is approximately 2.7 arc minutes away from NGC 9 . They are most likely unrelated stars , simply an optical binary . NGC 9 is a spiral galaxy about 140 million light years away in the Pegasus constellation. It was discovered on 27 September 1865 by Otto Struve. A spiral galaxy is a type of galaxy originally described by Edwin Hubble in his 1936 work "The Realm of the Nebulae" and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters. In observational astronomy, a double star or visual double is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. Otto Struve (August 12, 1897  April 6, 1963) was a astronomer. In Russian, his name is sometimes given as Otto Lyudvigovich Struve (  ); however, he spent most of his life and his entire scientific career in the United States. Otto was the descendant of famous astronomers of the Struve family; he was the son of Ludwig Struve, grandson of Otto Wilhelm von Struve and great-grandson of Friedrich Georg Wilhelm von Struve. He was also the nephew of Karl Hermann Struve. Friedrich Georg Wilhelm von Struve (15 April 1793  23 November 1864 (Julian calendar: November 11)) was a German, Russian astronomer from a famous dynasty. 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. 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. Otto Wilhelm von Struve (May 7, 1819 (Julian calendar: April 25)  April 14, 1905) was a Russian astronomer. In Russian, his name is normally given as Otto Vasil'evich Struve (  ). Together with his father, Friedrich Georg Wilhelm von Struve, Otto Wilhelm von Struve is considered a prominent 19th century astronomer who headed the Pulkovo Observatory between 1862 and 1889 and was a leading member of the Russian Academy of Sciences. 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.
candidates: 12 academy of sciences april association atmosphere august century constellation distance dome education family five galaxy government instrument julian calendar may natural science navigation november observatory october optical instrument optical telescope part physics planet plot realm region science sky spiral galaxy star surface system telescope tool union
answer: galaxy