View source for 19P/Borrelly

{{Short description|Periodic comet with 6 year orbit}}
{{Infobox planet
| name=19P/Borrelly
| background=#FFE0C2
| image=Comet Borrelly Nucleus.jpg
| image_scale=
| discoverer=[[Alphonse Borrelly]]
| discovered=December 28, 1904
| alt_names=1905 II; 1911 VIII; 1918 IV;<br/> 1925 VIII; 1932 IV; 1953 IV;<br/> 1960 V; 1967 VIII; 1974 VII;<br/> 1981 IV; 1987 XXXIII; 1994 XXX
| epoch=2022-08-09 ([[Julian date|JD]] 2459800.5)
| moid={{Convert|0.36|AU|e6km|abbr=unit|lk=on}}
| semimajor= 3.61 AU
| perihelion= 1.306 AU<ref name=MPC/>
| time_periastron=2028-Dec-11<ref name="Horizons2028"/><br/>February 1, 2022 (last)<ref name=MPC>{{mpc|19p}}</ref>
| aphelion= 5.90 [[Astronomical Unit|AU]]<ref name=MPC/>
| eccentricity=0.6377
| period= 6.85 [[Julian year (astronomy)|yr]]
| inclination=29.30°
| dimensions=8×4×4&nbsp;km<ref name=Weaver2003>{{cite journal
 |last         = Weaver
 |first        = H. A.
 |author2      = Stern, S.A.
 |author3      = Parker, J. Wm.
 |title        = Hubble Space Telescope STIS Observations of Comet 19P/BORRELLY during the Deep Space 1 Encounter
 |journal      = The Astronomical Journal
 |publisher    = The American Astronomical Society
 |volume       = 126
 |issue        = 1
 |pages        = 444–451
 |date         = 2003
 |doi          = 10.1086/375752
 |bibcode      = 2003AJ....126..444W
 |doi-access   = free
 }}</ref>
  |density=0.3 [[Gram|g]]/cm<sup>3</sup><ref name=Britt2006>{{cite web
  |date=2006
  |title=Small Body Density and Porosity: New Data, New Insights
  |publisher=Lunar and Planetary Science XXXVII
  |author=D. T. Britt
  |author2=G. J. Consol-magno SJ
  |author3=W. J. Merline
  |url=http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2214.pdf
  |access-date=2008-12-16| archive-url= https://web.archive.org/web/20081217064607/http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2214.pdf| archive-date= 17 December 2008 | url-status= live}}</ref>
  | mean_radius = 2.4 km<ref>{{Cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Com_19PBorrelly&Display=Facts&System=Metric |title=19P/Borrelly: Facts & Figures|access-date=2014-08-08 |archive-url=https://web.archive.org/web/20140809140735/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Com_19PBorrelly&Display=Facts&System=Metric |archive-date=2014-08-09 |url-status=dead }}</ref>
  |mass=2{{e|13}} [[Kilogram|kg]]<ref>Using the [[Volume#Formulas|volume of an ellipsoid]] of 8x4x4km * a [[rubble pile]] density of 0.3 g/cm<sup>3</sup> yields a mass (m=d*v) of 2.0E+13 kg.</ref>
  |albedo=0.03<ref name=dark>{{cite web
  |date=2001-11-29
  |title=Comet Borrelly Puzzle: Darkest Object in the Solar System
  |publisher=[[Space.com]]
  |author=Robert Roy Britt
  |url=http://www.space.com/scienceastronomy/solarsystem/borrelly_dark_011129.html
  |access-date=2008-12-16| archive-url= https://web.archive.org/web/20090122074028/http://www.space.com/scienceastronomy/solarsystem/borrelly_dark_011129.html| archive-date= 22 January 2009 | url-status= dead}}</ref>
}}

{| class=wikitable style="text-align:center; font-size:11px; float:right; margin:2px"
|- bgcolor= style="font-size: smaller;"
| colspan="8" style="text-align:center;"|'''Perihelion distance<br/>at recent epochs'''<ref name=MPC/>
|-
! [[Epoch (astronomy)|Epoch]] !! [[Perihelion]]<br/>([[Astronomical unit|AU]])
|-
| 2028 || 1.310<ref name="Horizons2028"/>
|-
| 2022 || 1.306
|-
| 2015 || 1.349
|-
| 2008 || 1.355
|}

'''Comet Borrelly''' {{IPAc-en|b|Q|'|r|E|l|i}} or '''Borrelly's Comet''' (official designation: '''19P/Borrelly''') is a [[comet]] with a period of 6.85 years that was visited by the spacecraft [[Deep Space 1]] in 2001. The comet last came to [[perihelion]] (closest approach to the Sun) on February 1, 2022<ref name=MPC/><ref name="Yoshida"/> and will next come to perihelion on December 11, 2028.<ref name="Horizons2028"/>

{| class="wikitable" style="text-align: center; font-size: 0.9em;"
|+19P/Borrelly closest Earth approach on 2028-Dec-05
! Date & time of<br />closest approach
! Earth distance<br/>([[Astronomical unit|AU]])
! Sun distance<br/>(AU)
! Velocity<br/>wrt Earth<br/>(km/s)
! Velocity<br/>wrt Sun<br/>(km/s)
! Uncertainty<br />region<br />([[3-sigma]])
! Reference
|-
| 2028-Dec-05 19:12 ± 6 min || {{Convert|0.413|AU|e6km e6mi LD|abbr=unit|lk=on}} || {{Convert|1.31|AU|e6km e6mi LD|abbr=unit}} || 17.3 || 33.3 || ± 41 thousand&nbsp;km || <small>[https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27DES%3D19P%3BCAP%27&START_TIME=%272028-Dec-05%2019:12%27&STOP_TIME=%272028-Dec-06%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2719,20,22,39%27 Horizons]</small>
|}

Deep Space 1 returned images of the comet's nucleus from 3400 kilometers away. At 45 meters per pixel, it was the highest resolution view ever seen of a comet up until that time.<ref>{{cite web |last1=Beatty |first1=Kelly |title=Meet Comet Borrelly |url=https://skyandtelescope.org/astronomy-news/meet-comet-borrelly/ |website=Sky & Telescope |access-date=27 January 2021 |date=25 June 2004}}</ref>

== Discovery ==
The comet was discovered by [[Alphonse Borrelly]] during a routine search for comets at [[Marseille]], [[France]] on December 28, 1904.

== Exploration ==
=== Deep Space 1 flyby ===
[[File:Animation of Deep Space 1 trajectory.gif|thumb|left|Animation of Deep Space 1{{'s}} trajectory from 24 October 1998 to 31 December 2003<br />{{legend2|magenta| Deep Space 1}}{{·}}{{legend2|lime|[[9969 Braille]]}}{{·}}{{legend2|royalblue|[[Earth]]}}{{·}}{{legend2|Cyan|19P/Borrelly}}]]
On September 21, 2001 the spacecraft [[Deep Space 1]], which was launched to test new equipment in space, performed a flyby of Borrelly. It was steered toward the comet during the extended mission of the craft, and presented an unexpected bonus for the mission scientists. Despite the failure of a system that helped determine its orientation, Deep Space 1 managed to send back to [[Earth]] what were, at the time, the best images and other science data from a comet.
{{Clear|left}}
[[File:Orbits of periodic comets.svg|thumb|The orbits of three [[periodic comet]]s, 1P/Halley, 19P/Borrelly and [[153P/Ikeya-Zhang]], set against the orbits of the [[outer planets]].]]

== References ==
{{Reflist|refs=

<ref name="Horizons2028">{{cite web
  |title=Horizons Batch for 19P/Borrelly (90000304) on 2028-Dec-11
  |publisher=[[JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |type=Perihelion occurs when rdot flips from negative to positive
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000304%27&START_TIME=%272028-Dec-11%2020:00%27&STOP_TIME=%272028-Dec-12%27&STEP_SIZE=%2710%20minutes%27&QUANTITIES=%2719%27
  |archive-url=https://web.archive.org/web/20230211125953/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000304%27&START_TIME=%272028-Dec-11%2021:00%27&STOP_TIME=%272028-Dec-12%27&STEP_SIZE=%2710%20minutes%27&QUANTITIES=%2719%27
  |archive-date=2023-02-11
  |url-status=live
  |accessdate=2023-07-06}} (JPL#K222/14 Soln.date: 2023-May-25)</ref>

<ref name="Yoshida">{{cite web
  |date=2021-04-03
  |title=19P/Borrelly
  |publisher=Seiichi Yoshida's Comet Catalog
  |author=Seiichi Yoshida
  |url=http://www.aerith.net/comet/catalog/0019P/index.html
  |access-date=2022-06-15}}</ref>

}} <!-- end of reflist -->

== External links ==
* http://jcometobs.web.fc2.com/pcmtn/0019p.htm
* [http://cometography.com/pcomets/019p.html 19P] – [[Gary W. Kronk]]'s Cometography
* [https://minorplanetcenter.net/cgi-bin/returnprepeph.cgi?d=c&o=0019P Elements and Ephemeris for 19P/Borrelly] – [[Minor Planet Center]]

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{{DEFAULTSORT:Borrelly, 019P}}
[[Category:Periodic comets]]
[[Category:Numbered comets|0019]]
[[Category:Comets visited by spacecraft]]
[[Category:Comets in 2015|019P]]
[[Category:Astronomical objects discovered in 1904|19041228]]