2I/Borisov

"Comet Borisov" redirects here. For other comets discovered by Gennadiy Borisov, see Comet Borisov (disambiguation).

2I/Borisov
Borisov in October 2019[a]
Discovery
Discovered byGennadiy Borisov
Discovery siteMARGO observatory, Nauchnyy, Crimea
Discovery date30 August 2019
Earliest precovery:
13 December 2018
Orbital characteristics
Epoch5 January 2020[3]
Observation arc389 days
Number of
observations		1191
Perihelion2.00662±0.00002 AU
Semi-major axis−0.85132±0.00007 AU[b]
Eccentricity3.3570±0.0002 (JPL)
3.357 (MPC)[4]
Inclination44.0535°±0.0001°
308.1500°±0.0003°
Argument of
periapsis		209.1244°±0.0004°
Last perihelion8 December 2019[3][4][5]
Next perihelioninterstellar object
Earth MOID1.09302 AU
Jupiter MOID2.388 AU
Physical characteristics
Dimensions≤ 0.5 km[6](for an albedo of 0.04)
≤ 0.4 km[7]

2I/Borisov, originally designated C/2019 Q4 (Borisov),[8] is the first observed rogue comet and the second observed interstellar interloper after ʻOumuamua.[9][10] It was discovered by the Crimean amateur astronomer and telescope maker Gennadiy Borisov on 29 August 2019 UTC (30 August local time).[11][12]

2I/Borisov has a heliocentric orbital eccentricity of 3.36 and is not bound to the Sun.[13] The comet passed through the ecliptic of the Solar System at the end of October 2019, and made its closest approach to the Sun at just over 2 AU on 8 December 2019.[3][14] The comet passed closest to Earth on 28 December 2019.[15] In November 2019, astronomers from Yale University said that the comet's tail was 14 times the size of Earth, and stated, "It's humbling to realize how small Earth is next to this visitor from another solar system."[16]

  1. ^ Cite error: The named reference hubblesite-1 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference hubblesite-2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference JPL-Data was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference MPC-DB was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Gray234 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Jewitt2019b was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Hui2020 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference MPEC2019-S72 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference EA-20191014 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Grossman2019 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference NYT-20191207a was invoked but never defined (see the help page).
  12. ^ "Krymskiy astronom zayavil, chto otkrytaya im kometa izmenit nazvaniye" Крымский астроном заявил, что открытая им комета изменит название [Crimean astronomer says that the comet discovered by him will be renamed]. RIA Novosti РИА Новости (in Russian). 16 September 2019. para. 5. Retrieved 16 September 2019.
  13. ^ Cite error: The named reference NYT-20191224 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference NYT-20191207b was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Guzik2019 was invoked but never defined (see the help page).
  16. ^ Shelton, Jim (26 November 2019). "New image offers close-up view of interstellar comet". Yale University. Retrieved 7 December 2019.


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