12P/Pons–Brooks

Lore & Background

Comet Pons–Brooks was conclusively discovered at Marseilles Observatory in July 1812 by Jean-Louis Pons, and independently found by Vincent Wisniewski and Alexis Bouvard shortly after. Its orbital period was initially calculated at about 70 years, later refined to 70.68 years by Johann Franz Encke. The comet was identified with earlier observations: a comet recorded by the Chinese in 1385 and by Paolo dal Pozzo Toscanelli in 1457, both reaching magnitude 3 or brighter. It may also have been recorded in 245 CE, though this is uncertain. So-Yeon Park and Jong-Chul Chae suggested additional sightings in 1313 and 1668, but Maik Meyer argued that the 1313 apparition would have been dim and in the wrong constellation, and the 1668 comet was likely a sungrazing comet incompatible with Pons–Brooks.

On its 1883 return, William Robert Brooks accidentally discovered the comet, which was later identified with the 1812 object. An outburst in September 1883 brightened it from magnitude 10–11 to 8–8.5. It became visible to the naked eye in November 1884, reaching magnitude 3, with further outbursts in January 1884. The 1954 apparition saw multiple outbursts, including one in March 1954, and the comet reached magnitude 6.4 on 23 April. Its meteor stream passed near Earth on 10 December 1954. In 2020, the comet was recovered at magnitude 23 by the Lowell Discovery Telescope. During the 2024 apparition, it underwent 14 well-documented outbursts, brightening to magnitude 3.8 near perihelion. The Thai National Radio Telescope detected OH maser emissions in March 2024, and the SWAN instrument on SOHO measured peak water production of 1.7×10^30 sec−1 on 14 April 2024.

Reader's Guide

Comet Pons–Brooks is significant as one of the brightest periodic comets, with a well-documented history spanning centuries. Its 71-year orbit places it among Halley-type comets, and its brightness—reaching absolute magnitude about 5—makes it a notable object for both professional and amateur observers. The comet's orbital evolution is stable between 1740 and 2167, with a 1:6 resonance with Jupiter and a Tisserand invariant of 0.60. Its aphelion lies just beyond Neptune's orbit at 33.6 AU. The comet shares orbital elements with 122P/de Vico, leading to speculation that the latter may have split from Pons–Brooks centuries ago. Other comets with similar periods include 13P/Olbers, 23P/Brorsen–Metcalf, and 1P/Halley. Over the next 100,000 years, the orbit is expected to remain stable, though there is a 0.5 percent chance that non-gravitational perturbations could shift it into a retrograde or sungrazing orbit. The nucleus size is estimated at 5.6 km in radius by David C. Jewitt, based on outburst power, while Quanzhi Ye gave an upper limit of 17.0 km from photometric measurements. The comet's legacy includes its role in understanding cometary outbursts and its historical observations dating back to the 14th century.

Did You Know?

• Comet Pons–Brooks was observed in 1385 and 1457, with the 1385 apparition recorded by the Chinese in Ming Shilu.
• The comet underwent 14 well-documented outbursts between June 2023 and April 2024.
• Its nucleus radius is estimated at 5.6 km by David C. Jewitt, with an upper limit of 17.0 km from Quanzhi Ye.
• The comet's orbit is locked in a 1:6 resonance with Jupiter.