8" Alvan Clark & Sons telescope at Chabot Space and Science Center.

Alvan Clark (March 8, 1804 – August 19, 1887), born in Ashfield, Massachusetts, was an American astronomer and telescope maker. He was a portrait painter and engraver, but at the age of 40 become involved in telescope making. Using glass blanks made by Mantois of Paris his firm, Alvan Clark & Sons, ground lenses for refracting telescopes, including the largest in the world at the time: the 18.5-inch at Dearborn Observatory at the Old University of Chicago (the lens was originally intended for Ole Miss), the 26-inch at the United States Naval Observatory, the 30-inch at Pulkovo Observatory (destroyed in the Siege of Leningrad; only the lens survives), the 36-inch telescope at Lick Observatory (still third-largest) and later the 40-inch at Yerkes Observatory, which remains the largest successful refracting telescope in the world. One of Clark's sons, Alvan Graham Clark, discovered the dim companion of Sirius. His other son was George Bassett Clark; both sons were partners in the firm. Image File history File links Alvanclark-leah. ... Image File history File links Alvanclark-leah. ... An editor has expressed a concern that the subject of the article does not satisfy one of the following guidelines for inclusion on Wikipedia: If you are familiar with the subject matter, please expand the article to establish its notability, citing reliable sources, so as to avoid its being considered... March 8 is the 67th day of the year in the Gregorian Calendar (68th in Leap years). ... 1804 was a leap year starting on Sunday (see link for calendar). ... August 19 is the 231st day of the year (232nd in leap years) in the Gregorian Calendar. ... 1887 (MDCCCLXXXVII) is a common year starting on Saturday (click on link for calendar) of the Gregorian calendar or a common year starting on Monday of the Julian calendar. ... Ashfield is a town located in Franklin County, Massachusetts. ... A giant Hubble mosaic of the Crab Nebula. ... 50 cm refracting telescope at Nice Observatory. ... Image:Refracting telescope scan. ... The University of Chicago, now known as the Old University of Chicago, was a Baptist college founded in 1857 by Stephen Douglas. ... The Lyceum The University of Mississippi (also known as Ole Miss) is public, coeducational research university located near Oxford, Mississippi. ... Aerial view of USNO. The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States. ... The Pulkovo Space Observatory (Пу́лковская астрономи́ческая обсервато́рия in Russian), the principal space observatory of the Russian Academy of Sciences, located 19 km south of Saint Petersburg on Pulkovo Heights (75 m above the sea level), at , . It is a World Heritage Site [1]. The observatory was opened in 1839 (chief architect - Alexander Bryullov). ... Combatants Axis Powers, Spanish Blue Division Soviet Union Commanders Wilhelm Ritter von Leeb Georg von Kuechler Kliment Voroshilov Georgy Zhukov Strength 725,000 930,000 Casualties Unknown 300,000 military, 16,470 civilians from bombings and estimated 1 million civilians from starvation The Siege of Leningrad (Russian: блокада Ленинграда) was the German... The Lick Observatory is an astronomical observatory, owned and operated by the University of California. ... The Yerkes Observatory is an astronomy observatory of the University of Chicago, in Williams Bay, Wisconsin. ... Alvan Graham Clark (July 10, 1832 – June 9, 1897), born in Fall River, Massachusetts, was an American astronomer and telescope-maker. ... Sirius (α CMa / α Canis Majoris / Alpha Canis Majoris) is the brightest star in the night-time sky, with a visual apparent magnitude of −1. ... George Bassett Clark (February 14, 1827 - December 20, 1891) was an American astronomer. ...

Craters on the Moon and on Mars are named in his honor. Tycho crater on Earths moon. ... Bulk composition of the Moons mantle and crust estimated, weight percent Oxygen 42. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...

See also

• List of astronomical instrument makers
• List of largest optical refracting telescopes

The following is a list of Astronomical Instrument Makers, along with lifespan and country of work, if available. ... Paris 1900 exposition refractor. ...

References

• http://reference.allrefer.com/encyclopedia/C/Clark-Al.html
• Alvan Clark & Sons, Artists in Optics, by Deborah Jean Warner and Robert B. Ariail, ISBN 0-943396-46-8