instance_of ngc 8
Otto Wilhelm von Struve ( ___MASK49___ 7 , 1819 ( Julian ___MASK94___ : ___MASK8___ ___MASK59___ )  ___MASK8___ 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 ___MASK50___ between 1862 and 1889 and was a leading member of the Russian Academy of Sciences . In observational astronomy , a ___MASK41___ 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 . Earth , otherwise known as the world , is the third ___MASK77___ from the Sun and the only object in the Universe known to ___MASK45___ life . It is the densest ___MASK77___ in the Solar ___MASK38___ and the largest of the four terrestrial planets . NGC 8 is a ___MASK41___ ___MASK38___ ( 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 . A spiral ___MASK85___ is a type of ___MASK85___ 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 . Astronomy is a natural ___MASK36___ that studies celestial objects and phenomena . It applies ___MASK70___ , ___MASK80___ , 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 . In astronomy and ___MASK3___ , the celestial ___MASK46___ is an imaginary ___MASK46___ of arbitrarily large radius , concentric with Earth . All objects in the observer ' s sky can be thought of as projected upon the inside ___MASK96___ of the celestial ___MASK46___ , as if it were the underside of a ___MASK6___ or a hemispherical screen . The celestial ___MASK46___ is a practical tool for spherical astronomy , allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant . A ___MASK17___ is a luminous sphere of plasma held together by its own gravity . The nearest ___MASK17___ 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 ___MASK17___ catalogues that identify the known stars and provide standardized stellar designations . However , most of the stars in the Universe , including all stars outside our ___MASK85___ , the Milky Way , are invisible to the naked eye from Earth . Indeed , most are invisible from Earth even through the most powerful telescopes . NGC 9 is a spiral ___MASK85___ about 140 million light years away in the Pegasus constellation . It was discovered on 27 September 1865 by Otto Struve . A ___MASK91___ is an optical ___MASK9___ that aids in the observation of remote objects by collecting ___MASK65___ ( 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 . Otto Struve ( ___MASK22___ 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 . Gustav Wilhelm Ludwig Struve ( ___MASK55___ ___MASK43___ , 1858  ___MASK55___ 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 (    ). Friedrich Georg Wilhelm von Struve ( 15 ___MASK8___ 1793  23 ___MASK55___ 1864 ( Julian ___MASK94___ : ___MASK55___ 11 )) was a German , Russian astronomer from a famous dynasty . The International Astronomical ___MASK35___ ( IAU UAI ) is an international ___MASK73___ 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 ___MASK96___ features on them . The Struve ___MASK86___ ( pronounced in German , in Russian ) were a dynasty of ___MASK54___ generations of astronomers from the 18th to 20th centuries . Members of the ___MASK86___ were also prominent in chemistry , ___MASK18___ and diplomacy . A ___MASK25___ is formally defined as a region of the celestial ___MASK46___ , with boundaries laid down by the International Astronomical Union ( IAU ). The ___MASK25___ areas mostly had their origins in Western - traditional patterns of stars from which the constellations take their names . Karl Hermann Struve ( ___MASK66___ 3 , 1854  ___MASK22___ 12 , 1920 ) was a Russian astronomer . In Russian , his name is sometimes given as " German Ottovich Struve " (    ) or " German Ottonovich Struve " (    ).