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 (lost minor planets), 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.
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, Fate of comets). 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.an extinct comet that can resemble an asteroid (see Comets §
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.
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 (also P/2006 M3), discovered by Edward Emerson Barnard on June 24, 1889, was rediscovered after 116 years in 2006.
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. magnitude. [ needs update ]It is expected to remain observable with large telescopes until perhaps 2020, by which time it will be nearing 30th
Comets that have been lost or which have disappeared have names beginning with a D, according to current naming conventions.
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.
|Name(s)||Initially discovered||Period (years)||Last seen||Recovered||Fate|
|D/1770 L1 (Lexell)||1770||5.6||Probably 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 (529688) 2010 JL33 is most likely its inert remnant.|
|3D/Biela||1772||6.6||1852||Broke up in two fragments (1846), then thousands, creating the Andromedids meteor shower|
|27P/Crommelin||1818||27.9||1873||1928||Three independent discoveries linked by Crommelin in 1930|
|289P/Blanpain||1819||5.2||2003||Lost since 1819 discovery due to faintness; rediscovered in 2003 thanks to good viewing conditions; first identified as asteroid 2003 WY25, 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–Gambart||1827||180||2012||Period 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–NEAT||1844||7.3||1894, 1965||2002||Lost several times due to perturbations by Jupiter|
|122P/de Vico||1846||74.4||1995||Not observed on first predicted return in 1921; recovered in 1995 after 149 years and 2 orbits|
|5D/Brorsen||1846||5.5||1879||Lost since 1879 despite good orbit computations|
|80P/Peters–Hartley||1846||8.1||1982||Recovered in 1982 after 136 years and 17 orbits; regularly observed since then|
|20D/Westphal||1852||61.9||1913||Expected in 1976 but not observed; next possible return in 2038|
|109P/Swift–Tuttle||1862||133.3||1992||Recovered 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–Tuttle||1865||33.2||1965||Recovered in 1965 after 99 years and 3 orbits; matches earlier observations of 1366 and 1699; source of the Leonids meteor shower|
|11P/Tempel–Swift–LINEAR||1869||6.4||1908||2001||Recovered 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–Fujikawa||1881||9.0||1978||2014||Recovered in 1978 after 97 years and 11 orbits, then lost again and recovered in 2014 after 4 more orbits|
|15P/Finlay||1886||6.5||1926||1953||Regularly observed since 1953|
|177P/Barnard||1889||118.8||2006||Recovered after 117 years in a single orbit|
|206P/Barnard–Boattini||1892||5.8||2008||Recovered in 2008 after 116 years and 20 orbits; not seen on predicted return in 2014; next perihelion in 2021|
|17P/Holmes||1892||6.9||1906||1964||Regularly observed since 1964; large outburst in 2007|
|205P/Giacobini (D/1896 R2)||1896||6.7||2008||Recovered in 2008 after 112 years and 17 orbits; seen in 2015 as predicted; three visible fragments|
|18D/Perrine–Mrkos||1896||6.75||1909, 1968||1955||Lost after 1909, recovered in 1955 and lost again since 1968|
|113P/Spitaler||1890||7.1||1993||Recovered in 1993 after 103 years and 15 orbits; regularly observed since 1994 perihelion|
|97P/Metcalf–Brewington||1906||10.5||1991||Recovered in 1991 after 84 years and 11 orbits; orbital period lengthened by Jupiter in 1993|
|69P/Taylor||1915||6.95||1976||Recovered in 1976 after 61 years and 9 orbits; regularly observed since 1977 perihelion|
|25D/Neujmin||1916||5.4||1927||Only seen twice; lost since 1927|
|34D/Gale||1927||11.0||1938||Only seen twice; lost since 1938|
|73P/Schwassmann–Wachmann||1930||5.4||1979||Broke up into 4 fragments in 1995 and dozens in 2006, yielding the Tau Herculids meteor shower|
|57P/du Toit–Neujmin–Delporte||1941||6.4||1970||Recovered in 1970 after 29 years and 5 orbits; observed regularly since 1983|
|107P/Wilson–Harrington||1949||4.3||1992||Lost 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–Lemmon||1966||18.5||2012||First discovered on plates from 1960; recovered in 2012 after 3 orbits; perihelion in 2013|
|85D/Boethin||1975||11.2||1986||Only seen twice; lost since 1986 (expected in 1997 and 2008 but not observed), officially demoted in 2017|
|75D/Kohoutek||1975||6.6||1988||Only seen three times; lost since 1988|
|157P/Tritton||1978||6.4||2003||Recovered in 2003 after 25 years and 4 orbits; regularly observed since then|
|83D/Russell||1979||6.1||1985||Only seen twice; lost since 1985, probably due to a close encounter with Jupiter in 1988|
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
Comet Hale–Bopp is a comet that was perhaps the most widely observed of the 20th century and one of the brightest seen for many decades.
Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–76 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the only naked-eye comet that can appear twice in a human lifetime. Halley last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061.
Comet Hyakutake is a comet, discovered on 31 January 1996, that passed very close to Earth in March of that year. It was dubbed The Great Comet of 1996; its passage near the Earth was one of the closest cometary approaches of the previous 200 years. Hyakutake appeared very bright in the night sky and was widely seen around the world. The comet temporarily upstaged the much anticipated Comet Hale–Bopp, which was approaching the inner Solar System at the time.
Comet Encke, or Encke's Comet, is a periodic comet that completes an orbit of the Sun once every 3.3 years. Encke was first recorded by Pierre Méchain on 17 January 1786, but it was not recognized as a periodic comet until 1819 when its orbit was computed by Johann Franz Encke. Like Halley's Comet, it is unusual in its being named after the calculator of its orbit rather than its discoverer. Like most comets, it has a very low albedo, reflecting only 4.6% of the light its nucleus receives, although comets generate a large coma and tail that can make them much more visible during their perihelion. The diameter of the nucleus of Encke's Comet is 4.8 km.
Biela's Comet or Comet Biela was a periodic Jupiter-family comet first recorded in 1772 by Montaigne and Messier and finally identified as periodic in 1826 by Wilhelm von Biela. It was subsequently observed to split in two and has not been seen since 1852. As a result, it is currently considered to have been destroyed, although remnants appeared to have survived for some time as a meteor shower, the Andromedids.
A sungrazing comet is a comet that passes extremely close to the Sun at perihelion – sometimes within a few thousand kilometres of the Sun's surface. Although small sungrazers can completely evaporate during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong evaporation and tidal forces they experience often lead to their fragmentation.
The Kreutz sungrazers are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. A Kreutz sungrazers's aphelion is about 170 AU from the Sun; these sungrazers make their way from the distant outer Solar System from a patch in the sky in Canis Major, to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.
5D/Brorsen was a periodic Jupiter-family comet discovered on February 26, 1846, by Danish astronomer Theodor Brorsen. The perihelion of 5D/Brorsen was February 25, just a day before its discovery, and it passed closest to Earth on March 27, at a distance of 0.52 AU. As a result of this close encounter to Earth the comet's coma diameter increased. Johann Friedrich Julius Schmidt estimated it as 3 to 4 arcminutes across on March 9, and 8 to 10 arcminutes across on the 22nd of that same month. On April 22, it was about 20 degrees from the north celestial pole. By the end of this first apparition the orbital period was calculated as 5.5 years. It was discovered that a close approach to Jupiter in 1842 put it in its discovery orbit.
11P/Tempel–Swift–LINEAR is a periodic Jupiter-family comet in the Solar System.
Comet Finlay is a periodic comet with an orbital period of 6 years discovered by William Henry Finlay on September 26, 1886. The next perihelion passage is July 13, 2021 when the comet will have a solar elongation of 54 degrees at approximately apparent magnitude 10. It last came to perihelion on December 27, 2014, at around magnitude 10. Of the numbered periodic comets, the orbit of 15P/Finlay has one of the smallest minimum orbit intersection distances with the orbit of Earth (E-MOID). In 2060 the comet will pass about 6 million km from Earth.
An extinct comet is a comet that has expelled most of its volatile ice and has little left to form a tail and coma. In a dormant comet, rather than being depleted, any remaining volatile components have been sealed beneath an inactive surface layer.
Comet Arend or 50P/Arend is a periodic comet in the Solar System which was discovered on October 4, 1951. It was discovered by astronomer Sylvain Julien Victor Arend at the Royal Observatory of Belgium located in the municipality of Uccle. The comet was illustrated at approximately a magnitude of 14 and also exhibited a nucleus within a coma 14 arc seconds across. From its discovery, the comet has had 7 perihelions with its last return of Earth recorded on November 1, 2007. The comet's next perihelion will be in the year 2016.
Comet Swift–Tuttle is a large periodic comet with a 1995 (osculating) orbital period of 133 years that is in a 1:11 orbital resonance with Jupiter. It fits the classical definition of a Halley-type comet with an orbital period between 20 and 200 years. The comet was independently discovered by Lewis Swift on July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862.
Comets have been observed for over 2,000 years. During that time, several different systems have been used to assign names to each comet, and as a result many comets have more than one name.
A great comet is a comet that becomes exceptionally bright. There is no official definition; often the term is attached to comets such as Halley's Comet, which during certain appearances are bright enough to be noticed by casual observers who are not looking for them, and become well known outside the astronomical community. Great comets appear at irregular, unpredictable intervals, on average about once per decade. Although comets are officially named after their discoverers, great comets are sometimes also referred to by the year in which they appeared great, using the formulation "The Great Comet of ...", followed by the year.
C/2014 UN271 (Bernardinelli-Bernstein), or simply 2014 UN271 or the Bernardinelli–Bernstein comet, is a large Oort cloud comet discovered by astronomers Pedro Bernardinelli and Gary Bernstein in archival images from the Dark Energy Survey. When first imaged in October 2014, the object was 29 AU (4.3 billion km) from the Sun, almost as far as Neptune's orbit and the greatest distance at which a comet has been discovered. During 2021, it will approach the Sun from a distance of 20.8 AU (3.1 billion km) to 19.5 AU (2.9 billion km) and will reach its perihelion of 10.9 AU (just outside of Saturn's orbit) in January 2031. The current 3-sigma uncertainty in the comet's distance from the Sun is ±60000 km. It is potentially the largest Oort cloud comet discovered. It will not be visible to the naked eye because it will not enter the inner Solar System.