Alvan Graham Clark observes Sirius B
- When
- 1862
- Where
- Cambridgeport, Massachusetts
- Episodes
- 1
Alvan Graham Clark observed Sirius B on 31 January 1862 using an 18.5-inch refractor. The observation occurred in Cambridgeport, Massachusetts, during testing, contradicting legacy claims of Evanston. The telescope was later delivered to Northwestern University in Evanston, Illinois.
Episodes
Background and detail
Background. Sirius B is a white dwarf companion to Sirius A, the brightest star in the night sky. It is a dense remnant of an intermediate-mass star, with mass equivalent to the Sun but size comparable to Earth. Sirius B is the closest white dwarf to Earth, making it a significant target for astronomical observation.
Observation. Alvan Graham Clark, an American astronomer and telescope-maker, made the first observation of Sirius B on 31 January 1862. He used an 18.5-inch aperture refractor, the largest in the United States at the time, to detect the magnitude 8 companion star.
Instrument. The telescope used for the observation was an 18.5-inch refractor built by Clark. After the observation in Cambridgeport, Massachusetts, this instrument was delivered to the Dearborn Observatory at Northwestern University in Evanston, Illinois, where it remains in use.
People involved
- Alvan Graham Clark · Astronomer and telescope-maker
Sources
- Alvan Graham Clark Wikipedia, revision of 2026-09-06
- Sirius B Wikipedia, revision of 2026-09-27
Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.