24P/Schaumasse

Lore & Background

By the end of 1912, the comet was recognized as a short-period comet with an estimated return of 7.1 years, later recalculated to 8 years. The 1919 return was recovered by Gaston Fayet at magnitude 10.5. The 1927 approach was magnitude 12, but the comet was missed in 1935. In 1937, a close pass to Jupiter increased its orbital period slightly. The comet reached magnitude 15 on its 1943–1944 apparition. During the 1951–1952 apparition, it was brighter than expected, reaching about magnitude 6 in February 1952.

The comet was missed in 1968 and 1976. It was speculated that the 1952 brightness increase indicated a problem that led to its vanishing. During the 1984 apparition, James B. Gibson recovered the comet at Palomar Observatory. Also in 1984, it was reported that Elizabeth Roemer had found a comet on a photograph from 27 December 1976; orbital calculations by Brian G. Marsden confirmed that image featured Comet Schaumasse. The comet was not observed during the 2009 unfavorable apparition. It passed within 0.025 AU of Ceres on 22 March 2010. During the 2017 apparition it reached magnitude 10. On 25 October 2025, it passed about 1 degree from Jupiter. It came to perihelion on 8 January 2026 with a solar elongation of 94 degrees and brightened to about magnitude 9. Two small outbursts, brightening the comet by 0.7 and 1.1 magnitudes, were recorded in March and May 2026. Around 25 October 2100 it should pass about 0.17 AU from Mars.

Reader's Guide

24P/Schaumasse is notable as the first of three comets discovered by Alexandre Schaumasse and as a Jupiter-family comet with a well-documented but erratic observational history. Its brightness has varied significantly across apparitions, from magnitude 6 in 1952 to being missed entirely in 1935, 1968, and 1976. The recovery of the comet from a 1976 photograph by Elizabeth Roemer, confirmed by Brian G. Marsden, resolved a period of apparent disappearance. The comet's close approach to Ceres in 2010 and its 2025 passage near Jupiter highlight its dynamic interactions within the solar system. Its nucleus size estimates have been revised downward from 2.6 km to 1.82 km based on newer calculations. Spectroscopic analysis in 1992 detected emissions of CN, C3, C2, and NH in its coma, with significant variations in C2 within 10,000 km of the nucleus. The comet's legacy includes its role in demonstrating the challenges of tracking short-period comets and the value of archival photographic plates.

Did You Know?

• 24P/Schaumasse passed within 0.025 AU (4 million km) of the dwarf planet Ceres on 22 March 2010.
• The comet was recovered from a 27 December 1976 photograph by Elizabeth Roemer, confirmed by Brian G. Marsden.
• Two small outbursts in March and May 2026 brightened the comet by 0.7 and 1.1 magnitudes respectively.
• Spectroscopic analysis in 1992 detected CN, C3, C2, and NH emissions in its coma.