Great Comet of 1760

Lore & Background

The Great Comet of 1760 was first seen on 7 January 1760 by Abbe Chevalier at Lisbon. Charles Messier also spotted the comet on 8 January 1760 in Paris, by the sword of Orion. This was Messier's third comet discovery. Messier observed the comet for a total of 6 days and gave it a magnitude rating of 2.0, making it easily visible to the unaided eye, and an elongation angle of 140 degrees.

The comet approached Earth to within approximately 0.0682 AU on January 8, 1760, which as of 2006 was the 17th closest known approach by a comet. Two days later, James Short recorded his sighting of the comet while it was in the constellation Eridanus, noting that it moved about 2 degrees per day towards the west.

Messier faced opposition from Navy astronomer Joseph Nicholas Delisle, who had employed Messier from October 1751. Delisle would not publish the discovery Messier had made, continuing a mistrust that had developed because Delisle had been slow to publish Messier's work in 1759. Messier had independently rediscovered Halley's Comet on 21 January 1759, but because Messier doubted the correctness of Delisle's path, Delisle instructed Messier to continue observing and refused to announce the discovery. Delisle later changed his mind and announced the discovery on 1 April 1759, but other French astronomers discredited the claim, labeling it an April Fools' joke. Delisle retired in 1765.

Reader's Guide

The Great Comet of 1760 holds significance primarily through its association with Charles Messier, for whom it was the third comet discovery. Its observation history is intertwined with the contentious relationship between Messier and his employer, Joseph Nicholas Delisle. Delisle's refusal to publish Messier's discovery of this comet continued a pattern of mistrust that began with Messier's independent rediscovery of Halley's Comet in 1759. In that earlier case, Delisle delayed announcing the discovery until 1 April 1759, leading other French astronomers to dismiss it as an April Fools' joke. The comet's legacy also includes its status as the 51st comet to have a calculated orbit and its ranking as the 17th closest known approach to Earth by a comet up to 2006. James Short's subsequent observation provided additional positional data. As of June 2008, the comet was about 216 AU from the Sun, indicating its long-term trajectory. The episode illustrates the personal and institutional conflicts that could shape early cometary astronomy.

Did You Know?

• The Great Comet of 1760 was the 51st comet to have a calculated orbit.
• Charles Messier discovered this comet on 8 January 1760, making it his third comet discovery.
• The comet approached Earth to within 0.0682 AU on January 8, 1760, the 17th closest known approach up to 2006.
• Messier's employer Joseph Nicholas Delisle refused to publish the discovery, continuing a pattern of mistrust.