Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage[1] (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) [it]. 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 [n]D instead of [n]P, such as 3D/Biela 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 they were named for a person who calculated their orbits (the orbit computers). The long-term orbits of comets can be difficult to calculate due to errors in the known trajectory that can accumulate from perturbations from the planets. 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 and tail. Unlike a long-period comet, the next perihelion 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 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, or "A" for an object that was either mistakenly identified as a comet, but is actually a minor planet,[1] or for an object on a hyperbolic orbit that does not show cometary activity.[2] Some lists retain the "C" prefix for comets of periods larger than about 30 years until their return is confirmed.[3]
While Jupiter-family comets are officially defined by 2 < TJupiter < 3, they can also be loosely defined as any comet with a period of less than 20 years, a relatively low inclination, and an orbit coinciding loosely with that of Jupiter. These comets are often patchily observed, as orbital interactions with the planet 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 albedos and frequent proximity to the Sun compared to Oort Cloud comets cause them to much more quickly become depleted of volatiles, making them comparatively dimmer than comets with longer orbital periods.
Irish republican (1875–1916) Michael Joseph O'RahillyMícheál Seosamh Ó RathailleMichael Joseph O'Rahilly (The O'Rahilly) c. 1913-1916Born(1875-04-22)22 April 1875Ballylongford, County Kerry, IrelandDied29 April 1916(1916-04-29) (aged 41)Dublin, IrelandResting placeGlasnevin CemeteryNationalityIrishOther namesThe O'Rahilly, Ua RathghailleEducationClongowes Wood CollegeOrganization(s)Irish VolunteersGaelic LeagueSpouse(s)Nancy O'Rahilly (m. 1899)ChildrenBobbyRichardAodogánNiallM...
مسجد شاه جهان Shah Jahan Mosque مسجد شاه جهان إحداثيات 51°19′18″N 0°32′51″W / 51.3218°N 0.5475°W / 51.3218; -0.5475 معلومات عامة القرية أو المدينة ووكينغ، سري الدولة إنجلترا تاريخ بدء البناء 1889م التصميم والإنشاء المهندس المعماري غوتليب ويهيلم ليتنر معلومات أخرى تعديل مصدري - تعديل ...
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Voce principale: Football Club Crotone. F.C. CrotoneStagione 2006-2007Sport calcio Squadra Crotone Allenatore Elio Gustinetti (1ª-21ª; 23ª) Guido Carboni (22ª; 24ª-42ª) All. in seconda Carlo Cimicata[1] Presidente Raffaele Vrenna Serie B21º posto (retrocesso in Serie C1) Coppa Italia3° turno Maggiori presenzeCampionato: Sedivec (37) Miglior marcatoreCampionato: Cariello, Sedivec (6) StadioStadio Ezio Scida 2005-2006 2007-2008 Si invita a seguire il modello di voce Questa...
Place in Acre, Mandatory PalestineAl-Damun الدامونDamun[1] 1870s map 1940s map modern map 1940s with modern overlay map A series of historical maps of the area around Al-Damun (click the buttons)Al-DamunLocation within Mandatory PalestineCoordinates: 32°52′37″N 35°10′59″E / 32.87694°N 35.18306°E / 32.87694; 35.18306Palestine grid167/254Geopolitical entityMandatory PalestineSubdistrictAcreDate of depopulation15–16 July 1948[4]A...
Miners' union in Wales South Wales Miners' FederationFounded24 October 1898; 125 years ago (1898-10-24)HeadquartersMaescyoed, PontypriddLocationUnited KingdomMembers 102 (2016)[1]Key peopleWayne Thomas (secretary)Kevin T. Thomas (chair)Parent organizationNational Union of Mineworkers The South Wales Miners' Federation (SWMF), nicknamed The Fed, was a trade union for coal miners in South Wales. It survives as the South Wales Area of the National Union of Mineworkers. ...
This is a list of foreign players in the EFL Championship, which commenced play in 2004. The following players must meet both of the following two criteria: Have played at least one Championship game. Players who were signed by Championship clubs, but only played in lower league, cup and/or European games, or did not play in any competitive games at all, are not included. Are considered foreign, i.e., outside Great Britain and Ireland, determined by the following: If a player has been capped...
For related races, see 1952 United States gubernatorial elections. 1952 Washington gubernatorial election ← 1948 November 4, 1952 1956 → Nominee Arthur B. Langlie Hugh Mitchell Party Republican Democratic Popular vote 567,822 510,675 Percentage 52.7% 47.4% County resultsLanglie: 50–60% 60–70%Mitchell: 50–60% Governor before election Arthur B. Langlie Republican El...
Country in Northern Europe This article is about the modern state. For other uses, see Latvia (disambiguation). Lettonia redirects here. For the Latvian student corporation, see Lettonia (corporation). Republic of LatviaLatvijas Republika (Latvian)Latvejas Republika (Latgalian)Lețmō Vabāmō (Livonian) Flag Coat of arms Anthem: Dievs, svētī Latviju! (Latvian)(God Bless Latvia!)Location of Latvia (dark green)– in Europe (green & dark ...
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Democratic Party Sint Maarten – news · newspapers · books · scholar · JSTOR (December 2009) (Learn how and ...
16th-century English dramatist, poet, and translator This article is about the English dramatist. For the American sportscaster, see Chris Marlowe. Christopher MarloweAnonymous portrait, possibly of Marlowe,at Corpus Christi College, CambridgeBornCanterbury, Kent, EnglandBaptised26 February 1564Died30 May 1593 (aged 29)Deptford, Kent, EnglandResting placeChurchyard of St. Nicholas, Deptford; unmarked; memorial plaques inside and outside churchAlma materCorpus Christi College, CambridgeOc...
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. (July 2013) (Learn how and when to remove this message) This article's lead section may be too short to adequately summarize the key points. Please consider expanding the l...
Jonathan Daniels4th White House Press SecretaryIn officeMarch 29, 1945 – May 15, 1945PresidentFranklin D. RooseveltHarry S. TrumanPreceded byStephen EarlySucceeded byCharlie Ross Personal detailsBornJonathan Worth Daniels(1902-04-26)April 26, 1902Raleigh, North Carolina, U.S.DiedNovember 6, 1981(1981-11-06) (aged 79)Hilton Head, South Carolina, U.S.Political partyDemocraticSpouse(s)Elizabeth BridgersLucy Billing CathcartChildren4 daughtersEducationUniversity of North Carolina,...
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This is a list of notable accidents and incidents involving military aircraft grouped by the year in which the accident or incident occurred. Not all of the aircraft were in operation at the time. For more exhaustive lists, see the Aircraft Crash Record Office, the Air Safety Network, or the Dutch Scramble Website Brush and Dustpan Database. Combat losses are not included, except for a very few cases denoted by singular circumstances. This transport-related list is incomplete; you can help b...