Template:Short description Template:Use mdy dates Template:Infobox scientist Alvan Graham Clark (July 10, 1832 – June 9, 1897) was an American astronomer and telescope-maker.
BiographyEdit
Alvan Graham Clark was born in Fall River, Massachusetts, the son of Alvan Clark, founder of Alvan Clark & Sons.<ref name=Cyclopaedia>Template:Cite book</ref>
On January 31, 1862, while testing a new Template:Convert aperture great refractor telescope in Cambridgeport, Massachusetts, Clark made the first ever observation of a white dwarf star. This discovery of Sirius B, or affectionately "the Pup", proved an earlier hypotheses (Friedrich Wilhelm Bessel in 1844) that Sirius, the brightest star in the night sky with an apparent magnitude of −1.46, had an unseen companion disturbing its motion. Clark used the largest refracting telescope lens in existence at the time, and the largest telescope in the United States, to observe the magnitude 8 companion.
Clark's 18.5 inch refracting telescope was then delivered to his customer, the landmark Dearborn Observatory of Northwestern University in Evanston, Illinois, where it is still being used today.<ref>Dearborn Observatory: History</ref>
Alvan Graham Clark died in Cambridge, Massachusetts on June 9, 1897.<ref>Template:Cite news</ref>
See alsoEdit
ReferencesEdit
- Template:Cite encyclopedia
- The Dearborn Telescope
- Sirius A & B: A Double Star System In The Constellation Canis Major
- Northwestern University Astronomy and Astrophysics – History of Dearborn Observatory Template:Webarchive
- Look south to see winter's brightest constellations