Alvan Graham Clark

Alvan Graham Clark

American astronomer and telescope maker
Date of Birth: 10.07.1832
Country: USA

  1. Biography of Alvan Graham Clark
  2. Discovery of Sirius B
  3. Contributions to Astronomy
  4. Legacy

Biography of Alvan Graham Clark

Alvan Graham Clark was an American astronomer and telescope manufacturer. He was born on January 31, 1862, in Cambridgeport, Massachusetts. Alvan was the younger son and business partner of Alvin Clark, a renowned telescope maker.

Discovery of Sirius B

On January 31, 1862, while testing a new 18-inch refracting telescope, Alvan Clark made a significant discovery. He observed and identified Sirius B, the companion star of Sirius, in his telescope. This star, with an apparent magnitude of 8, became the first white dwarf to be discovered.

Contributions to Astronomy

Alvan Graham Clark's discovery of Sirius B greatly contributed to the field of astronomy. This finding expanded our understanding of stellar systems and the existence of companion stars. His observations and research helped astronomers refine their knowledge of white dwarfs and their place in the universe.


Alvan Graham Clark's work as an astronomer and telescope manufacturer left a lasting impact on the scientific community. His precise and high-quality telescopes continue to be used by astronomers around the world. Alvan's dedication to his craft and his significant discovery of Sirius B have secured his place in the history of astronomy.