Comet tail

Dust or gases blown off a comet by solar wind in the inner solar system, leaving a visible trail

Diagram of a comet showing the dust tail, dust trail (or anti-tail), and ionized gas tail, which is formed by the solar wind flow.

Comet Lovejoy photographed in 2011 by astronaut Dan C. Burbank from the ISS

Comet Holmes (17P/Holmes) in 2007, showing blue ionized gas tail on right Animation of a comet's tail

A comet tail and coma are visible features of a comet when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them.

Blown solar downwind, two separate tails are formed: one composed of dust and the other of gases. They become visible through different phenomena: the dust reflects sunlight directly, and the gases glow from ionization. Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.

## Tail formation[edit]

A comet's orbit showing the different directions of the gas and dust tails as the comet passes the SunShowing how a comet may appear to exhibit a short tail pointing in the opposite direction to its type II or dust tail as viewed from Earth i.e. an antitail

In the outer Solar System, comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from the Hubble Space Telescope observations,[1][2] but these detections have been questioned,[3][4] and have not yet been independently confirmed. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. The streams of dust and gas thus released form a huge, extremely tenuous atmosphere around the comet called the coma, and the force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun.

The streams of dust and gas each form their own distinct tails, pointing in slightly different directions. The tail of dust is left behind in the comet's orbit in such a manner that it often forms a curved tail called the antitail, only when it seems that it is directed towards the Sun. At the same time, the ion tail, made of gases, always points along the streamlines of the solar wind as it is strongly affected by the magnetic field of the plasma of the solar wind. The ion tail follows the magnetic field lines rather than an orbital trajectory. Parallax viewing from the Earth may sometimes mean the tails appear to point in opposite directions.[5]

## Size[edit]

While the solid nucleus of comets is generally less than 30 km across, the coma may be larger than the Sun, and ion tails have been observed to extend 3.8 astronomical units (570 Gm; 350×10 ~~^~~ 6 mi).[6]

The Ulysses spacecraft made an unexpected pass through the tail of the comet C/2006 P1 (Comet McNaught), on February 3, 2007.[7] Evidence of the encounter was published in the October 1, 2007, issue of The Astrophysical Journal.[8]

## Magnetosphere[edit]

The observation of antitails contributed significantly to the discovery of solar wind.[9] The ion tail is the result of ultraviolet radiation ejecting electrons off particles in the coma. Once the particles have been ionised, they form a plasma which in turn induces a magnetosphere around the comet. The comet and its induced magnetic field form an obstacle to outward flowing solar wind particles. The comet is supersonic relative to the solar wind, so a bow shock is formed upstream of the comet (i.e. facing the Sun), in the flow direction of the solar wind. In this bow shock, large concentrations of cometary ions (called "pick-up ions") congregate and act to "load" the solar magnetic field with plasma. The field lines "drape" around the comet forming the ion tail.[10] (This is similar to the formation of planetary magnetospheres.)

## Tail loss[edit]

Comet Encke loses its tail

If the ion tail loading is sufficient, then the magnetic field lines are squeezed together to the point where, at some distance along the ion tail, magnetic reconnection occurs. This leads to a "tail disconnection event".[10] This has been observed on a number of occasions, notable among which was on the 20th of April 2007 when the ion tail of comet Encke was completely severed as the comet passed through a coronal mass ejection.[11] This event was observed by the STEREO spacecraft.[12] A disconnection event was also seen with C/2009 R1 (McNaught) on May 26, 2010.[13]

## Analogues[edit]

Mercury and Venus possess similar tails caused by interaction of the solar wind with their atmospheres. On January 29, 2013, ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to "the ion tail seen streaming from a comet under similar conditions."[14][15] The MESSENGER mission observed magnesium and sodium being primary components of the Mercury tail.[16]

## References[edit]

1. ^ Cochran, A. L.; Levison, H. F.; Stern, S. A.; Duncan, J. (1995). "The Discovery of Halley-sized Kuiper Belt Objects Using the Hubble Space Telescope". The Astrophysical Journal. 455: 342. arXiv:astro-ph/9509100. Bibcode:1995ApJ...455..342C. doi:10.1086/176581. S2CID 118159645.
2. ^ Cochran, A. L.; Levison, H. F.; Tamblyn, P.; Stern, S. A.; Duncan, J. (1998). "The Calibration of the Hubble Space Telescope Kuiper Belt Object Search: Setting the Record Straight". Astrophysical Journal Letters. 503 (1): L89. arXiv:astro-ph/9806210. Bibcode:1998ApJ...503L..89C. doi:10.1086/311515. S2CID 18215327.
3. ^ Brown, Michael E.; Kulkarni, S. R.; Liggett, T. J. (1997). "An Analysis of the Statistics of the Hubble Space Telescope Kuiper Belt Object Search". Astrophysical Journal Letters. 490 (1): L119. Bibcode:1997ApJ...490L.119B. doi:10.1086/311009.
4. ^ Jewitt, David C.; Luu, Jane; Chen, J. (1996). "The Mauna Kea-Cerro-Tololo (MKCT) Kuiper Belt and Centaur Survey". The Astronomical Journal. 112 (3): 1225. Bibcode:1996AJ....112.1225J. doi:10.1086/118093.
5. ^ McKenna, M. (May 20, 2008). "Chasing an Anti-Tail". Astronomy Sketch of the Day. Retrieved February 25, 2009.
6. ^ Yeomans, Donald K. (2005). "Comet". World Book Online Reference Center. World Book. Archived from the original on April 29, 2005. Retrieved December 27, 2008.
7. ^ "A chance encounter with a comet". Astronomy. October 2, 2007.
8. ^ Neugebauer; et al. (2007). "Encounter of the Ulysses Spacecraft with the Ion Tail of Comet MCNaught". The Astrophysical Journal. 667 (2): 1262–1266. Bibcode:2007ApJ...667.1262N. doi:10.1086/521019.
9. ^ Biermann, L. (1963). "The plasma tails of comets and the interplanetary plasma". Space Science Reviews. 1 (3): 553. Bibcode:1963SSRv....1..553B. doi:10.1007/BF00225271. S2CID 120731934.
10. ^ a b Carroll, B. W.; Ostlie, D. A. (1996). An Introduction to Modern Astrophysics. Addison-Wesley. pp. 864–874. ISBN 978-0-201-54730-6.
11. ^ "The Sun Rips Off a Comet's Tail". Science@NASA. October 1, 2007. Archived from the original on November 4, 2009. Retrieved October 20, 2009.
12. ^ Eyles, C. J.; Harrison, R. A.; Davis, C. J.; Waltham, N. R.; Shaughnessy, B. M.; Mapson-Menard, H. C. A.; Bewsher, D.; Crothers, S. R.; Davies, J. A.; Rochus, P. (2009). "The Heliospheric Imagers Onboard the STEREO Mission". Solar Physics. 254 (2): 387–445. Bibcode:2009SoPh..254..387E. doi:10.1007/s11207-008-9299-0. S2CID 54977854.
13. ^ "Comet C/2009 R1 (McNaught) - Animation & Images". Remanzacco Observatory. May 30, 2010. Retrieved June 7, 2011.
14. ^ Staff (January 29, 2013). "When A Planet Behaves Like A Comet". ESA. Retrieved January 31, 2013.
15. ^ Kramer, Miriam (January 30, 2013). "Venus Can Have 'Comet-Like' Atmosphere". Space.com. Retrieved January 31, 2013.
16. ^ McClintock 2009, p. 610–611

## External links[edit]

Wikimedia Commons has media related to Comet tails.

* Comets at Curlie
* Comets page at NASA's Solar System Exploration
* International Comet Quarterly at Harvard.edu

* v
* t
* e

Comets

| Features|

* Nucleus
* Coma
* Tails
* Antitail
* Comet dust
* Meteor shower

|
|

Types|

* Periodic
* Numbered
* Lost
* Long period
* Halley-type
* Jupiter-family
* Encke-type
* Main-belt
* Non-periodic
* Near-parabolic
* Hyperbolic
* Unknown-orbit
* Great Comet
* Sungrazing (Kreutz)
* Extinct
* Exocomet
* Interstellar

Related|

* Naming of comets
* Observational history of comets
* Centaur
* Comet discoverers
* LINEAR
* Extraterrestrial atmosphere
* Oort cloud
* Small Solar System body
* Asteroid

Exploration|

* List of missions to comets
* List of comets visited by spacecraft

Latest|

* C/2023 P1 (Nishimura)
* C/2023 E1 (ATLAS)
* C/2023 A3 (Tsuchinshan–ATLAS)
* C/2022 E3 (ZTF)
* C/2021 O3 (PanSTARRS)
* C/2021 J1 (Maury-Attard)
* C/2021 A1 (Leonard)
* C/2020 F8 (SWAN)
* C/2020 F5 (MASTER)
* C/2020 F3 (NEOWISE)
* C/2019 Y4 (ATLAS)
* C/2019 Y1 (ATLAS)
* C/2019 U6 (Lemmon)
* 2I/Borisov
* C/2018 Y1 (Iwamoto)
* C/2018 C2 (Lemmon)
* C/2017 U7
* C/2017 K2 (PanSTARRS)
* C/2016 U1 (NEOWISE)
* C/2015 V2 (Johnson)
* C/2015 G2 (MASTER)
* C/2015 ER61 (PanSTARRS)
* C/2014 UN271 (Bernardinelli–Bernstein)
* C/2014 Q2 (Lovejoy)
* C/2014 Q1 (PanSTARRS)

Culture and
speculation|

* Antimatter comet
* Comets in fiction
* Comet vintages

Lists of comets (more)

| Periodic
comets|

| Until 1985
(all)|

* 1P/Halley
* 2P/Encke
* 3D/Biela
* 4P/Faye
* 5D/Brorsen
* 6P/d'Arrest
* 7P/Pons–Winnecke
* 8P/Tuttle
* 9P/Tempel
* 10P/Tempel
* 11P/Tempel–Swift–LINEAR
* 12P/Pons–Brooks
* 13P/Olbers
* 14P/Wolf
* 15P/Finlay
* 16P/Brooks
* 17P/Holmes
* 18D/Perrine–Mrkos
* 19P/Borrelly
* 20D/Westphal
* 21P/Giacobini–Zinner
* 22P/Kopff
* 23P/Brorsen–Metcalf
* 24P/Schaumasse
* 25D/Neujmin
* 26P/Grigg–Skjellerup
* 27P/Crommelin
* 28P/Neujmin
* 29P/Schwassmann–Wachmann
* 30P/Reinmuth
* 31P/Schwassmann–Wachmann
* 32P/Comas Solà
* 33P/Daniel
* 34D/Gale
* 35P/Herschel–Rigollet
* 36P/Whipple
* 37P/Forbes
* 38P/Stephan–Oterma
* 39P/Oterma
* 40P/Väisälä
* 41P/Tuttle–Giacobini–Kresák
* 42P/Neujmin
* 43P/Wolf–Harrington
* 44P/Reinmuth
* 45P/Honda–Mrkos–Pajdušáková
* 46P/Wirtanen
* 47P/Ashbrook–Jackson
* 48P/Johnson
* 49P/Arend–Rigaux
* 50P/Arend
* 51P/Harrington
* 52P/Harrington–Abell
* 53P/Van Biesbroeck
* 54P/de Vico–Swift–NEAT
* 55P/Tempel–Tuttle
* 56P/Slaughter–Burnham
* 57P/du Toit–Neujmin–Delporte
* 58P/Jackson–Neujmin
* 59P/Kearns–Kwee
* 60P/Tsuchinshan
* 61P/Shajn–Schaldach
* 62P/Tsuchinshan
* 63P/Wild
* 64P/Swift–Gehrels
* 65P/Gunn
* 66P/du Toit
* 67P/Churyumov–Gerasimenko
* 68P/Klemola
* 69P/Taylor
* 70P/Kojima
* 71P/Clark
* 72P/Denning–Fujikawa
* 73P/Schwassmann–Wachmann
* 74P/Smirnova–Chernykh
* 75D/Kohoutek
* 76P/West–Kohoutek–Ikemura
* 77P/Longmore
* 78P/Gehrels
* 79P/du Toit–Hartley
* 80P/Peters–Hartley
* 81P/Wild
* 82P/Gehrels
* 83D/Russell
* 84P/Giclas
* 85D/Boethin

|

After 1985
(notable)|

* 88P/Howell
* 92P/Sanguin
* 96P/Machholz
* 97P/Metcalf–Brewington
* 103P/Hartley
* 107P/Wilson–Harrington
* 108P/Ciffréo
* 109P/Swift–Tuttle
* 122P/de Vico
* 126P/IRAS
* 141P/Machholz
* 144P/Kushida
* 147P/Kushida–Muramatsu
* 153P/Ikeya–Zhang
* 156P/Russell–LINEAR
* 161P/Hartley–IRAS
* 168P/Hergenrother
* 169P/NEAT
* 177P/Barnard
* 178P/Hug–Bell
* 205P/Giacobini
* 209P/LINEAR
* 238P/Read
* 246P/NEAT
* 252P/LINEAR
* 255P/Levy
* 273P/Pons–Gambart
* 289P/Blanpain
* 311P/PanSTARRS
* 322P/SOHO
* 323P/SOHO
* 332P/Ikeya–Murakami
* 333P/LINEAR
* 354P/LINEAR
* 362P
* 460P/PanSTARRS

Comet-like
asteroids|

* 596 Scheila
* 2060 Chiron (95P)
* 4015 Wilson–Harrington (107P)
* 7968 Elst–Pizarro (133P)
* 165P/LINEAR
* 166P/NEAT
* 167P/CINEOS
* 60558 Echeclus (174P)
* 118401 LINEAR (176P)
* 238P/Read
* 259P/Garradd
* 311P/PanSTARRS
* 324P/La Sagra
* 331P/Gibbs
* 354P/LINEAR
* 358P/PANSTARRS
* P/2013 R3 (Catalina-PANSTARRS)
* (300163) 2006 VW139

Lost|

| Recovered|

* 11P/Tempel–Swift–LINEAR
* 15P/Finlay
* 17P/Holmes
* 27P/Crommelin
* 54P/de Vico–Swift–NEAT
* 55P/Tempel–Tuttle
* 57P/du Toit–Neujmin–Delporte
* 69P/Taylor
* 72P/Denning–Fujikawa
* 80P/Peters–Hartley
* 97P/Metcalf–Brewington
* 107P/Wilson–Harrington
* 113P/Spitaler
* 122P/de Vico
* 157P/Tritton
* 177P/Barnard
* 205P/Giacobini
* 206P/Barnard–Boattini
* 226P/Pigott–LINEAR–Kowalski
* 271P/van Houten–Lemmon
* 289P/Blanpain

|

Destroyed|

* 3D/Biela
* D/1993 F2 (Shoemaker–Levy 9)

Not found|

* D/1770 L1 (Lexell)
* 5D/Brorsen
* 18D/Perrine–Mrkos
* 20D/Westphal
* 25D/Neujmin
* 34D/Gale
* 75D/Kohoutek
* 83D/Russell
* 85D/Boethin

Visited by
spacecraft|

* 21P/Giacobini–Zinner (1985)
* 1P/Halley (1986)
* 26P/Grigg–Skjellerup (1992)
* 19P/Borrelly (2001)
* 81P/Wild (2004)
* 9P/Tempel (2005, 2011)
* C/2006 P1 (2007)
* 103P/Hartley (2010)
* 67P/Churyumov–Gerasimenko (2014)

Near-Parabolic
comets
(notable)|

| Until 1990|

* C/-43 K1 (Caesar's Comet)
* X/1106 C1 (Great Comet of 1106)
* C/1264 N1 (Great Comet of 1264)
* C/1402 D1 (Great Comet of 1402)
* C/1471 Y1 (Great Comet of 1472)
* C/1577 V1 (Great Comet of 1577)
* C/1652 Y1
* C/1680 V1 (Great Comet of 1680, Kirsch's Comet, Newton's Comet))
* C/1702 H1 (Comet of 1702)
* C/1729 P1 (Comet of 1729, Comet Sarabat)
* C/1743 X1 (Great Comet of 1744, Comet Klinkenberg-Chéseaux)
* C/1760 A1 (Great Comet of 1760)
* C/1769 P1 (Great Comet of 1769)
* C/1807 R1 (Great Comet of 1807)
* C/1811 F1 (Great Comet of 1811)
* C/1819 N1 (Great Comet of 1819)
* C/1823 Y1 (Great Comet of 1823)
* C/1843 D1 (Great March Comet of 1843)
* C/1847 T1 (Miss Mitchell's Comet)
* C/1858 L1 (Comet Donati)
* C/1861 G1 (Comet Thatcher)
* C/1861 J1 (Great Comet of 1861)
* C/1865 B1 (Great Southern Comet of 1865)
* X/1872 X1 (Pogson's Comet)
* C/1874 H1 (Comet Coggia)
* C/1881 K1 (Comet Tebbutt)
* C/1882 R1 (Great Comet of 1882)
* C/1887 B1 (Great Southern Comet of 1887)
* C/1901 G1 (Great Comet of 1901)
* C/1910 A1 (Great January Comet of 1910)
* C/1911 O1 (Brooks)
* C/1911 S3 (Beljawsky)
* C/1927 X1 (Skjellerup–Maristany)
* C/1931 P1 (Ryves)
* C/1941 B2 (de Kock-Paraskevopoulos)
* C/1947 X1 (Southern Comet)
* C/1948 V1 (Eclipse)
* C/1956 R1 (Arend–Roland)
* C/1957 P1 (Mrkos)
* C/1961 O1 (Wilson-Hubbard) [de]
* C/1961 R1 (Humason)
* C/1962 C1 (Seki-Lines)
* C/1963 A1 (Ikeya)
* C/1963 R1 (Pereyra)
* C/1964 N1 (Ikeya)
* C/1965 S1 (Ikeya-Seki)
* C/1969 T1 (Tago-Sato-Kosaka) [de]
* C/1969 Y1 (Bennett)
* C/1970 K1 (White–Ortiz–Bolelli)
* C/1973 E1 (Kohoutek)
* C/1975 V1 (West)
* C/1980 E1 (Bowell)
* C/1983 H1 (IRAS–Araki–Alcock)
* C/1989 W1 (Aarseth-Brewington)
* C/1989 X1 (Austin)
* C/1989 Y1 (Skorichenko–George)

|

After 1990|

* C/1990 K1 (Levy)
* C/1992 J1 (Spacewatch–Rabinowitz)
* C/1993 Y1 (McNaught–Russell)
* C/1995 O1 (Hale–Bopp)
* C/1996 B2 (Hyakutake)
* C/1997 L1 (Zhu–Balam)
* C/1998 H1 (Stonehouse)
* C/1998 J1 (SOHO)
* C/1999 F1 (Catalina)
* C/1999 S4 (LINEAR)
* C/2000 WM1 (LINEAR)
* C/2001 A2 (LINEAR)
* C/2001 OG108 (LONEOS)
* C/2001 Q4 (NEAT)
* C/2002 T7 (LINEAR)
* C/2002 V1 (NEAT)
* C/2004 F4 (Bradfield)
* C/2004 Q2 (Machholz)
* C/2006 A1 (Pojmański)
* C/2006 M4 (SWAN)
* C/2006 P1 (McNaught)
* C/2007 E2 (Lovejoy)
* C/2007 F1 (LONEOS)
* C/2007 N3 (Lulin)
* C/2007 Q3 (Siding Spring)
* C/2007 W1 (Boattini)
* C/2009 F6 (Yi–SWAN)
* C/2009 R1 (McNaught)
* C/2010 X1 (Elenin)
* C/2011 L4 (PANSTARRS)
* C/2011 W3 (Lovejoy)
* C/2012 E2 (SWAN)
* C/2012 F6 (Lemmon)
* C/2012 K1 (PANSTARRS)
* C/2012 S1 (ISON)
* C/2013 A1 (Siding Spring)
* C/2013 R1 (Lovejoy)
* C/2013 US10 (Catalina)
* C/2013 V5 (Oukaimeden)
* C/2014 E2 (Jacques)
* C/2014 Q1 (PanSTARRS)
* C/2014 Q2 (Lovejoy)
* C/2015 ER61 (PanSTARRS)
* C/2015 V2 (Johnson)
* C/2017 K2 (PanSTARRS)
* 1I/2017 U1 ʻOumuamua
* C/2018 Y1 (Iwamoto)
* 2I/Borisov
* C/2019 U6 (Lemmon)
* C/2019 Y4 (ATLAS)
* C/2020 F3 (NEOWISE)
* C/2020 F8 (SWAN)
* C/2021 A1 (Leonard)
* C/2022 E3 (ZTF)
* C/2023 P1 (Nishimura)

After 1910
(by name)|

* Aarseth-Brewington
* Arend–Roland
* Austin
* Beljawsky
* Bennett
* Boattini
* Borisov
* Bowell
* Bradfield
* Brooks
* Catalina
* C/1999 F1
* C/2013 US10
* de Kock–Paraskevopoulos
* Eclipse
* Elenin
* Hale-Bopp
* Humason
* Hyakutake
* Ikeya
* C/1963 A1
* C/1964 N1
* Ikeya-Seki
* IRAS–Araki–Alcock
* ISON
* Iwamoto
* Jacques
* Johnson
* Kohoutek
* Lemmon
* C/2012 F6
* C/2018 C2
* C/2019 U6
* Leonard
* Levy
* LINEAR
* C/1999 S4
* C/2000 WM1
* C/2001 A2
* C/2002 T7
* LONEOS
* C/2001 OG108
* C/2007 F1
* Lovejoy
* C/2007 E2
* C/2011 W3
* C/2013 R1
* C/2014 Q2
* Lulin
* Machholz
* McNaught
* C/2006 P1
* C/2009 R1
* McNaught–Russell
* Mrkos
* NEAT
* C/2001 Q4
* C/2002 V1
* NEOWISE
* Nishimura
* Oukaimeden
* ʻOumuamua
* Pan-STARRS
* C/2011 L4
* C/2012 K1
* 311P/PanSTARRS
* C/2014 Q1
* C/2015 ER61
* C/2017 K2
* Pereyra
* Pojmański
* Ryves
* Seki–Lines
* Siding Spring
* C/2007 Q3
* C/2013 A1
* Skjellerup–Maristany
* Skorichenko–George
* SOHO
* Southern
* Spacewatch–Rabinowitz
* Stonehouse
* SWAN
* C/2006 M4
* C/2012 E2
* C/2020 F8
* Tago-Sato-Kosaka [de]
* West
* White–Ortiz–Bolelli
* Wilson–Hubbard [de]
* Yi–SWAN
* Zhu–Balam
* ZTF

* Category

* v
* t
* e

Small Solar System bodies

Minor planets|

* Designation
* Groups
* List
* Moon
* Meanings of names

Asteroid|

* Active
* Aten asteroid
* Asteroid belt
* Family
* Jupiter trojan
* Near-Earth
* Spectral types

Distant minor planet|

*     * Centaur
* Neptune trojan
* Damocloid
* Trans-Neptunian object
* Detached
* Kuiper belt
* Oort cloud
* Scattered disc

Comets|

* Extinct
* Great
* Halley-type
* Hyperbolic
* Long-period
* Lost
* Near-parabolic
* Periodic
* Sungrazing

Other|

* Cosmic dust
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