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Periodic comets (also known as short-period comets) are
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 with
orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting pla ...
s of less than 200 years or that have been observed during more than a single
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 (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes used to mean any comet with a periodic orbit, even if greater than 200 years. Periodic comets receive a permanent number prefix usually after the second perihelion passage, which is why there are a number of unnumbered periodic comets, such as P/2005 T5 (Broughton). Comets that are not observed after a number of perihelion passages, or presumed to be destroyed, are given the D designation, and likewise comets given a periodic number and subsequently lost are given instead of , such as
3D/Biela 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 ...
or 5D/Brorsen. In nearly all cases, comets are named after their discoverers, but in a few cases such as 2P/Encke and
27P/Crommelin Comet Crommelin, also known as Comet Pons-Coggia-Winnecke-Forbes, is a periodic comet with an orbital period of almost 28 years. It fits the classical definition of a Halley-type comet with (20 years <
perturbations from the planets, and in the days before electronic computers some people dedicated their entire careers to this. Even so, quite a few comets were lost because their orbits are also affected by non-gravitational effects such as the release of gas and other material that forms the comet's
coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
and tail. Unlike a
long-period 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 are ...
, the next
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 of a numbered periodic comet can be predicted with a high degree of accuracy. Periodic comets sometimes bear the same name repeatedly (e.g. the nine Shoemaker–Levy comets or the twenty-four
NEAT Neat may refer to: * Neat (bartending), a single, unmixed liquor served in a rocks glass * Neat, an old term for horned oxen * Neat Records, a British record label * Neuroevolution of augmenting topologies (NEAT), a genetic algorithm (GA) for th ...
comets); the IAU system distinguishes between them either through the number prefix or by the full designation (e. g. 181P and 192P/Shoemaker–Levy are both "Comet Shoemaker–Levy"). In the literature, an informal numbering system is applied to periodic comets (skipping the non-periodic ones), thus 181P and 192P are known as Comet Shoemaker–Levy 6 and Comet Shoemaker–Levy 1, respectively. Non-periodic Shoemaker–Levy comets are interleaved in this sequence: C/1991 B1 between 2 and 3, C/1991 T2 between 5 and 6, C/1993 K1 and C/1994 E2 after Shoemaker–Levy 9. In comet nomenclature, the letter before the "/" is either "C" (a non-periodic comet), "P" (a periodic comet), "D" (a comet that has been lost or has disintegrated), "X" (a comet for which no reliable orbit could be calculated —usually historical comets), "I" for an
interstellar object An interstellar object is an astronomical object (such as an asteroid, a comet, or a rogue planet, but not a star) in interstellar space that is not gravitationally bound to a star. This term can also be applied to an object that is on an inter ...
, or "A" for an object that was either mistakenly identified as a comet, but is actually a
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
, or for an object on a hyperbolic orbit that does not show cometary activity. Some lists retain the "C" prefix for comets of periods larger than about 30 years until their return is confirmed.Comet names and designations
/ref>


List of Halley-type comets


List of unnumbered Jupiter-Family comets

While
Jupiter-family 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 ar ...
s are officially defined by 2 < T
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 ...
< 3, they can also be loosely defined as any comet with a period of less than 20 years, a relatively low
inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...
, and an orbit coinciding loosely with that of Jupiter. These comets are often patchily observed, as orbital interactions with the
planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
often cause comets' orbits to become perturbed, causing them to not be found at the expected position in the sky and subsequently lost. Additionally, their low cometary
albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refle ...
s and frequent proximity to the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
compared to
Oort Cloud The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from ...
comets cause them to much more quickly become depleted of volatiles, making them comparatively
dimmer A dimmer is a device connected to a light fixture and used to lower the brightness of the lighting, light. By changing the voltage waveform applied to the lamp, it is possible to lower the luminous intensity, intensity of the light output. Alt ...
than comets with longer orbital periods.


See also

*
List of comets by type This is a list of comets (bodies that travel in Elliptic orbit, elliptical, Parabolic trajectory, parabolic, and sometimes Hyperbolic trajectory, hyperbolic orbits and display a Comet tail, tail behind them) listed by type. Comets are sorted into ...
*
List of numbered comets This is a list of periodic comets that were numbered by the Minor Planet Center after having been observed on at least two occasions. Their orbital periods vary from 3.2 to 366 years. there are 436 numbered comets (1P–436P), most of them being ...
*
List of non-periodic comets The following is a list of comets with a very high eccentricity (generally 0.99 or higher) and a period of over 1,000 years that do not quite have a high enough velocity to escape the Solar System. Often, these comets, due to their extreme semimaj ...


References


External links


Minor Planet Center Periodic Comet Numbers






(periodic and non-periodic) {{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System
Periodic comets Periodicity or periodic may refer to: Mathematics * Bott periodicity theorem, addresses Bott periodicity: a modulo-8 recurrence relation in the homotopy groups of classical groups * Periodic function, a function whose output contains values tha ...
de:Liste der Kometen#Periodische Kometen lb:Koméitelëschten#Periodesch Koméiten