A lost comet is one which was not detected during its most recent

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

passage. This generally happens when data is insufficient to reliably calculate the

comet 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 ...

's location or if the

solar elongation In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet's position, in its orbital path around t ...

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 Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: * Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

. Some astronomers have specialized in this area, such as

Brian G. Marsden Brian Geoffrey Marsden (5 August 1937 – 18 November 2010) was a British astronomer and the longtime director of the Minor Planet Center (MPC) at the Center for Astrophysics Harvard & Smithsonian (director emeritus from 2006 to 2010). ...

, 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 Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...

. 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 The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

, as is believed to have happened in the case of

Lexell's Comet D/1770 L1, popularly known as Lexell's Comet after its orbit computer Anders Johan Lexell, was a comet discovered by astronomer Charles Messier in June 1770.Other comets named after their orbit computer, rather than discoverer, are 27P/Crommel ...

. 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,"If comets melt, why do they seem to last for long periods of time?"
''Scientific American'', November 16, 1998 an

extinct comet 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 la ...

that can resemble an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

''(see Comets § 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.Kronk, G.
5D/Brorsen
''Cometography.com'' 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 Biela's Comet or Comet Biela (official designation: 3D/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 ...

, 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 Comet 177P/Barnard, also known as Barnard 2, is a periodic comet with an orbital period of 122 years. It fits the classical definition of a Halley-type comet with (20 years <

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, and the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Sp ...

observed Hale–Bopp in 2022, 25 years since last approach, when it was 46.2 AU from the Sun.MPEC 2022-S20 : Observations and Orbits of Comets and A/ Objects
(2022 September 18) 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 Comet Shoemaker–Levy 9 ( formally designated D/1993 F2) broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a ...

, which collided with

in 1994.

References

External links

Lost periodic comets on Maik Meyer's home page
{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Comets

lost comets 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. ...