Comet Crommelin, also known as Comet Pons-Coggia-Winnecke-Forbes, is a

periodic 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 ...

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

with an

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 planets ...

of almost 28 years. It fits the classical definition of a Halley-type comet with (20 years <

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

< 200 years). It is named after the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

Andrew C. D. Crommelin who calculated its orbit in 1930. It is one of only four comets not named after their discoverer(s), the other three being Comets

Halley Halley may refer to: Science * Halley's Comet, officially designated 1P/Halley, a comet that becomes visible from Earth every 75-76 years * Halley (lunar crater), a lunar crater named after Edmond Halley * Halley (Martian crater), a Martian cra ...

, Encke, and Lexell. It next comes to

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(closest approach to the Sun) around May 27, 2039 when it will be near a maximum near-perihelion distance from Earth.

Observational history

The first observation was by

Jean-Louis Pons Jean-Louis Pons (24 December 176114 October 1831) was a French astronomer. Despite humble beginnings and being self-taught, he went on to become the greatest visual comet discoverer of all time: between 1801 and 1827 Pons discovered thirty-seven ...

(

Marseille Marseille (; ; see #Name, below) is a city in southern France, the Prefectures in France, prefecture of the Departments of France, department of Bouches-du-Rhône and of the Provence-Alpes-Côte d'Azur Regions of France, region. Situated in the ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

) on February 23, 1818, he followed the comet until February 27 but was prevented further by bad weather.

Johann Franz Encke Johann Franz Encke (; 23 September 179126 August 1865) was a German astronomer. Among his activities, he worked on the calculation of the periods of comets and asteroids, measured the distance from the Earth to the Sun, and made observations ...

attempted to calculate the orbit but was left with very large errors. In 1872, John R. Hind produced a rough orbital calculation and observed it was close to that of

Comet 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 t ...

, based on these observations, Edmund Weiss later speculated it may have been part of Biela's comet. The next observation was on November 10, 1873, by Jérôme E. Coggia (

), and again on November 11 by Friedrich A. T. Winnecke (

Strasbourg Strasbourg ( , ; ; ) is the Prefectures in France, prefecture and largest city of the Grand Est Regions of France, region of Geography of France, eastern France, in the historic region of Alsace. It is the prefecture of the Bas-Rhin Departmen ...

), but it was lost by November 16. Weiss and Hind took up the calculations and tried to match it again with the 1818 appearance. A third discovery was by Alexander F. I. Forbes (

Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

) on November 19, 1928, and confirmed by Harry E. Wood (

Union Observatory Union Observatory, also known as Transvaal Observatory, Republic Observatory and Johannesburg Observatory ( 078), is a defunct astronomical observatory in Johannesburg, South Africa that operated from 1903 to 1971. It is located on Observatory R ...

) on November 21. It was Crommelin who eventually established the orbit and finally linked the 1818 (Pons) and 1873 (Coggia-Winnecke) comets to it ''(also see

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. ...

)''. On its latest return, 27P/Crommelin was recovered on May 12, 2011, at

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

18.7 and peaked at magnitude 10.7 at perihelion on August 3. 27P/Crommelin was last observed in January 2012 and passed 1.5 AU from Saturn on July 11, 2015. The next

will be on May 27, 2039. Near perihelion the comet will be 0.74 AU from the Sun and 1.73 AU from Earth. This is about as far from Earth as the comet can get during perihelion. On December 22, 2120 it will pass from Earth.

References

External links

*
27P/Crommelin
at the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...

's Database
27P at Kronk's Cometography

Lightcurve
* 27P as seen by 10
GRAS-04
o
2011-05-30
(60 sec x 8) * 27P as seen by 20" RCOS o
2011-07-10
(30 sec x 12; Joseph Brimacombe) {{DEFAULTSORT:Crommelin, 027P Periodic comets 027P 0027 027P 027P 18180223