273P/Pons–Gambart
A retrograde Halley-type comet with a 186-year orbit.
273P/Pons–Gambart is a periodic comet that moves in a retrograde orbit. It was first spotted on 21 June 1827 by astronomers Jean-Louis Pons and Jean-Félix Adolphe Gambart. With an orbital period of 186 years, it qualifies as a Halley-type comet (period between 20 and 200 years). Its most recent perihelion occurred in December 2012, and its next is expected around August 2191.
The comet’s orbit was initially thought to be parabolic, but a 1917 recalculation suggested an elliptical path with a period of 64 years, plus or minus 10. This made the comet lost until 7 November 2012, when amateur astronomer Rob Matson found it in images from the SWAN instrument aboard SOHO. The earlier short-arc calculations had been completely off, as the comet had only a one-month observation arc with poor data—and that was its first return since 1827. It was last seen in April 2014, at a distance of 5.8 AU (870 million km) from the Sun.
Originally designated C/1827 M1, the comet was once suspected of being the same as C/1110 K1, based on the earlier, roughly 60-year period estimate. Among all numbered periodic comets, only 153P/Ikeya–Zhang has a longer orbital period.
Comet Pons–Gambart has been proposed as the parent body of the eta Eridanids meteor shower, though comet C/1852 K1 (Chacornac) appears to be a stronger candidate.
Quick Facts
- Discoverer
- Jean-Louis Pons / Jean-Félix Adolphe Gambart
- Discovery Date
- 21 June 1827
- Mpc Name
- C/1827 M1, P/2012 V4
- Orbit Ref
- jpldata · MPC
- Epoch
- 25 February 2023 (JD 2460000.5)
- Observation Arc
- 187–904 years
- Earliest Precovery Date
- May 1110?Hasegawa_1979
- Obs
- 1,185
- Perihelion
- 0.826 AU
- Aphelion
- 63.147 AU
- Semimajor
- 31.986 AU
- Eccentricity
- 0.97419
Facts from the source article.
Lore & Background
The comet's orbit was initially considered parabolic, but a recalculation in 1917 found it to be elliptical with an orbital period of 64 years, plus or minus 10 years uncertainty. The comet was considered lost until 7 November 2012, when amateur astronomer Rob Matson discovered it in images taken by the SWAN instrument on board SOHO. It was then identified that the pre-recovery short-arc orbital calculations were completely wrong because the comet had only a 1-month observation arc with poor data, and that 2012 return was the first perihelion after the 1827 apparition.
Before the 2012 return, when the comet was speculated to have a roughly 60-year orbit, it was suspected of possibly being comet C/1110 K1. The original name upon discovery was C/1827 M1. Of all the numbered periodic comets, only 153P/Ikeya–Zhang has a longer orbital period.
Reader's Guide
273P/Pons–Gambart holds significance as a rare long-period Halley-type comet with a retrograde orbit, discovered in the early 19th century by two prominent astronomers. Its history illustrates the challenges of comet orbit determination: initial parabolic assumptions and a flawed 64-year period estimate led to it being considered lost for nearly two centuries. The comet's recovery in 2012 by an amateur astronomer using SOHO's SWAN instrument corrected the orbital model, revealing a true 186-year period. This case underscores the value of modern space-based observations in recovering long-lost comets and refining orbital mechanics. The comet's legacy also includes a suggested link to the eta Eridanids meteor shower, though another comet is considered a better candidate. Its long orbital period places it among the most extreme numbered periodic comets.
Did You Know?
- The comet was first discovered on 21 June 1827 by Jean-Louis Pons and Jean-Félix Adolphe Gambart.
- Its orbit was initially considered parabolic, but recalculated in 1917 as elliptical with a 64-year period.
More in Periodic Comets, Part 2 1-24
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