Lost comet


A lost comet is one which was not detected during its most recent perihelion passage. This generally happens when data is insufficient to reliably calculate the comet's location or if the solar elongation is unfavorable near perihelion passage. The D/ designation is used for a periodic comet that no longer exists or is deemed to have disappeared.
Lost comets can be compared to lost asteroids, although calculation of comet orbits differs because of nongravitational forces, such as emission of jets of gas from the nucleus. Some astronomers have specialized in this area, such as Brian G. Marsden, who successfully predicted the 1992 return of the once-lost periodic comet Swift–Tuttle.

Overview

Loss

There are a number of reasons why a comet might be missed by astronomers during subsequent apparitions. Firstly, cometary orbits may be perturbed by interaction with the giant planets, such as Jupiter. This, along with nongravitational forces, can result in changes to the date of perihelion. Alternatively, it is possible that the interaction of the planets with a comet can move its orbit too far from the Earth to be seen or even eject it from the Solar System, as is believed to have happened in the case of Lexell's Comet. As some comets periodically undergo "outbursts" or flares in brightness, it may be possible for an intrinsically faint comet to be discovered during an outburst and subsequently lost.
Comets can also run out of volatiles. Eventually most of the volatile material contained in a comet nucleus evaporates away, and the comet becomes a small, dark, inert lump of rock or rubble, an extinct comet that can resemble an asteroid . This may have occurred in the case of 5D/Brorsen, which was considered by Marsden to have probably "faded out of existence" in the late 19th century.
, which broke up starting in 1995, as seen by the Hubble Space Telescope.
Comets are in some cases known to have disintegrated during their perihelion passage, or at other points during their orbit. The best-known example is Biela's Comet, which was observed to split into two components before disappearing after its 1852 apparition. In modern times 73P/Schwassmann–Wachmann has been observed in the process of breaking up.

Recovery

Occasionally, the discovery of an object turns out to be a rediscovery of a previously lost object, which can be determined by calculating its orbit and matching calculated positions with the previously recorded positions. In the case of lost comets this is especially tricky. For example, the comet 177P/Barnard, discovered by Edward Emerson Barnard on June 24, 1889, was rediscovered after 116 years in 2006.

Long period comets

Comets can be gone but not considered lost, even though they may not be expected back for hundreds or even thousands of years. With more powerful telescopes it has become possible to observe comets for longer periods of time after perihelion. For example, Comet Hale–Bopp was observable with the naked eye about 18 months after its approach in 1997. It is expected to remain observable with large telescopes until perhaps 2020, by which time it will be nearing 30th magnitude.
Comets that have been lost or which have disappeared have names beginning with a D, according to current naming conventions.

List

Comets are typically observed on a periodic return. When they do not they are sometimes found again, while other times they may break up into fragments. These fragments can sometimes be further observed, but the comet is no longer expected to return. Other times a comet will not be considered lost until it does not appear at a predicted time. Comets may also collide with another object, such as Comet Shoemaker–Levy 9, which collided with Jupiter in 1994.
NameInitially discoveredPeriod Last seenRecoveredFate
D/1770 L1 17705.6Probably lost due to a 1779 close encounter with Jupiter which might have greatly perturbed the orbit or even ejected the comet from the Solar System. The asteroid 2010 JL33 is most likely its inert remnant.
3D/Biela17726.61852Broke up in two fragments, then thousands, creating the Andromedids meteor shower
27P/Crommelin181827.918731928Three independent discoveries linked by Crommelin in 1930
289P/Blanpain18195.22003Lost since 1819 discovery due to faintness; rediscovered in 2003 thanks to good viewing conditions; first identified as asteroid, subsequently matched to the 1819 comet after 184 years and 35 orbits; confirmed by observations in 2013 and 2014 near perihelion; probable source of the Phoenicids meteor shower observed since 1956
273P/Pons–Gambart18271802012Period of roughly 64±10 years originally computed in 1917 was wrong; rediscovered after 185 years in a single orbit; possibly matches a Chinese observation in 1110
54P/de Vico–Swift–NEAT18447.31894, 19652002Lost several times due to perturbations by Jupiter
122P/de Vico184674.41995Not observed on first predicted return in 1921; recovered in 1995 after 149 years and 2 orbits
5D/Brorsen18465.51879Lost since 1879 despite good orbit computations
80P/Peters–Hartley18468.11982Recovered in 1982 after 136 years and 17 orbits; regularly observed since then
20D/Westphal185261.91913Expected in 1976 but not observed; next possible return in 2038
109P/Swift–Tuttle1862133.31992Recovered after 130 years as predicted in 1971 by Brian G. Marsden; retroactively matched to observations of 1737 in Europe and 188 AD and 68 BC in China; source of the Perseids meteor shower
55P/Tempel–Tuttle186533.21965Recovered in 1965 after 99 years and 3 orbits; matches earlier observations of 1366 and 1699; source of the Leonids meteor shower
11P/Tempel–Swift–LINEAR18696.419082001Recovered in 2001 after 93 years and 15 orbits; not observed in 2008 due to solar conjunction but seen again in 2014 as predicted
72P/Denning–Fujikawa18819.019782014Recovered in 1978 after 97 years and 11 orbits, then lost again and recovered in 2014 after 4 more orbits
15P/Finlay18866.519261953Regularly observed since 1953
177P/Barnard1889118.82006Recovered after 117 years in a single orbit
206P/Barnard–Boattini18925.82008Recovered in 2008 after 116 years and 20 orbits; not seen on predicted return in 2014; next perihelion in 2021
17P/Holmes18926.919061964Regularly observed since 1964; large outburst in 2007
205P/Giacobini 18966.72008Recovered in 2008 after 112 years and 17 orbits; seen in 2015 as predicted; three visible fragments
18D/Perrine–Mrkos18966.751909, 19681955Lost after 1909, recovered in 1955 and lost again since 1968
113P/Spitaler18907.11993Recovered in 1993 after 103 years and 15 orbits; regularly observed since 1994 perihelion
97P/Metcalf–Brewington190610.51991Recovered in 1991 after 84 years and 11 orbits; orbital period lengthened by Jupiter in 1993
69P/Taylor19156.951976Recovered in 1976 after 61 years and 9 orbits; regularly observed since 1977 perihelion
25D/Neujmin19165.41927Only seen twice; lost since 1927
34D/Gale192711.01938Only seen twice; lost since 1938
73P/Schwassmann–Wachmann19305.41979Broke up into 4 fragments in 1995 and dozens in 2006, yielding the Tau Herculids meteor shower
57P/du Toit–Neujmin–Delporte19416.41970Recovered in 1970 after 29 years and 5 orbits; observed regularly since 1983
107P/Wilson–Harrington19494.31992Lost for 30 years; rediscovered as a Mars-crosser asteroid in 1979; equated with the lost comet in 1992 while searching for precovery images
271P/van Houten–Lemmon196618.52012First discovered on plates from 1960; recovered in 2012 after 3 orbits; perihelion in 2013
85D/Boethin197511.21986Only seen twice; lost since 1986, officially demoted in 2017
75D/Kohoutek19756.61988Only seen three times; lost since 1988
157P/Tritton19786.42003Recovered in 2003 after 25 years and 4 orbits; regularly observed since then
83D/Russell19796.11985Only seen twice; lost since 1985, probably due to a close encounter with Jupiter in 1988