11P/Tempel–Swift–LINEAR
A periodic comet lost and recovered after nearly a century.
11P/Tempel–Swift–LINEAR is a periodic comet with an orbital period of 5.95 years and a diameter of roughly 1 km. It is notable for being discovered in the 19th century, later becoming a lost comet for decades, and then recovered in 2001 by the LINEAR program.
Quick Facts
- Discovery Ref
- IAUC_7779
- Discoverer
- Ernst Tempel · Lewis Swift · LINEAR
- Discovery Date
- 27 November 1869 · 11 October 1880 · 7 December 2001
- Mpc Name
- P/1869 W1, P/1880 T1 · P/2001 X3
- Designations
- 1869 III, 1880 IV · 1891 V, 1908 II · 1869c, 1880e, 1891d · 1908d
- Orbit Ref
- jpldata · MPC
- Epoch
- 21 November 2025 / (JD 2461000.5)
- Obs
- 1,365
- Perihelion
- 1.387 AU
- Aphelion
- 5.18 AU
- Semimajor
- 3.283 AU
- Eccentricity
- 0.57739
Facts from the source article.
Lore & Background
The comet was originally discovered by Ernst Wilhelm Leberecht Tempel on 27 November 1869 from his observatory at Marseille, with its perihelion then at about 1.063 AU from the Sun. Lewis Swift later observed it on 11 October 1880 from the Warner Observatory and recognized it as the same comet. After 1908, the comet became unobservable and was considered lost, due to a series of four close flybys of Jupiter between 1911 and 1946 that perturbed its orbit, making subsequent apparitions unfavorable. Brian G. Marsden computed an orbit based on observations from 1891 to 1908 and predicted a favorable return in 1963, but the comet remained unobserved. Further predictions were made by Marsden and Zdenek Sekanina in 1971, and by Shuichi Nakano in 1995. On 7 December 2001, an object designated P/2001 X3 was found by the Lincoln Near-Earth Asteroid Research (LINEAR) program; analysis of images taken between 10 September and 17 October 2001 confirmed it as the recovery of the lost comet Tempel–Swift. The comet was not observed during the 2008 apparition because perihelion occurred on the far side of the Sun, but it was observed during the 2014 and 2020 apparitions. For the 2026 perihelion passage, the comet was recovered on 6 August 2026.
Reader's Guide
11P/Tempel–Swift–LINEAR holds significance as a comet that was lost for most of the 20th century due to gravitational perturbations by Jupiter, then recovered through modern survey observations. Its recovery in 2001 by the LINEAR program demonstrated the ability of automated sky surveys to rediscover long-lost comets. The comet's orbit has been studied by several astronomers, including Brian G. Marsden, Zdenek Sekanina, and Shuichi Nakano, who attempted to predict its returns. The 2026 apparition offers a favorable viewing opportunity, with the comet reaching a solar elongation of 170 degrees and a declination of +26 at perihelion on 9 November 2026, and making a close approach to Earth on 11 November 2026 at a distance of 0.401 AU. It may brighten enough in late 2026 to become observable with smart telescopes.
Did You Know?
- Lewis Swift observed the same comet on 11 October 1880 and recognized it as Tempel's.
- The comet became lost after 1908 due to four close flybys of Jupiter between 1911 and 1946.
- It was recovered on 7 December 2001 by the LINEAR program as P/2001 X3.
More in Named Comets, Part 5 1-24
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