C/2013 A1 (Siding Spring)

For other uses, see Siding Spring.

C/2013 A1 (Siding Spring)
Comet Siding Spring as seen by Hubble on 11 March 2014
Discovery[1]
Discovered bySiding Spring Observatory
0.5-m Schmidt (E12)
Discovery date3 January 2013
Orbital characteristics[2][3][4]
Epoch30 October 2014 (JD 2456960.5)
Observation arc3.53 years
Number of
observations		449
Orbit typeOort cloud
Aphelion52000 AU (inbound)
13000 AU (outbound)
Perihelion1.39875 AU (q)
Eccentricity1.00043
Orbital periodseveral million years inbound
(Barycentric solution for epoch 1950)
~500000 years outbound
(Barycentric solution for epoch 2050)
Inclination129.033°
300.999°
Argument of
periapsis		2.449°
Last perihelion25 October 2014
TJupiter–0.919
Earth MOID0.3836 AU
Jupiter MOID3.6748 AU
Physical characteristics[2][5][6]
Dimensions~400–700 m (0.25–0.43 mi)
Comet total
magnitude (M1)		8.5
Comet nuclear
magnitude (M2)		12.0

C/2013 A1 (Siding Spring) is an Oort cloud comet discovered on 3 January 2013 by Robert H. McNaught at Siding Spring Observatory using the 0.5-meter (20 in) Uppsala Southern Schmidt Telescope.[1][7]

At the time of discovery it was 7.2 AU from the Sun and located in the constellation Lepus. Comet C/2013 A1 probably took millions of years to come from the Oort cloud. After leaving the planetary region of the Solar System, the post-perihelion orbital period (epoch 2050) is estimated to be roughly 1 million years.[4]

C/2013 A1 passed the planet Mars very closely on 19 October 2014, at a distance of 140,496.6 ± 4.0 km (87,300.5 ± 2.5 mi; 0.000939162 ± 2.7×10−8 au).[8] After its discovery, there was thought to be a chance of a collision with Mars, but this possibility was excluded when its orbit was determined with about a 200-day observation arc.[9]

All NASA Mars orbiters—including 2001 Mars Odyssey,[10] Mars Reconnaissance Orbiter[11] and MAVEN[12]—as well as ESA's orbiter, Mars Express,[13] and ISRO's orbiter, the Mars Orbiter Mission,[14] reported a healthy status after the comet flyby on 19 October 2014.[15][16] During the flyby, orbiters around Mars detected thousands of kilograms per hour of comet dust composed of magnesium, iron, sodium, potassium, manganese, nickel, chromium and zinc.[17] In addition, the comet nucleus was determined to be between 400 and 700 meters (0.2 and 0.4 mi),[5][6][17] much smaller than originally assumed. The nucleus rotates once every eight hours.[18]

  1. ^ a b Cite error: The named reference MPEC2013-A14 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference jpldata was invoked but never defined (see the help page).
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  4. ^ a b Cite error: The named reference barycenter was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference HiRISE141021 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Swift was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference NYT-20140804 was invoked but never defined (see the help page).
  8. ^ Farnocchia, D.; Chesley, S.R.; Micheli, M.; Delamere, W.A.; Heyd, R.S.; Tholen, D.J.; Giorgini, J.D.; Owen, W.M.; Tamppari, L.K. (2016). "High precision comet trajectory estimates: The Mars flyby of C/2013 A1 (Siding Spring)". Icarus. 266: 279–287. arXiv:1507.01980. Bibcode:2016Icar..266..279F. doi:10.1016/j.icarus.2015.10.035. ISSN 0019-1035. S2CID 118874989.
  9. ^ Cite error: The named reference esa was invoked but never defined (see the help page).
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  13. ^ Cite error: The named reference ESA-20141020 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference ISRO MOM safe after Mars comet flyby was invoked but never defined (see the help page).
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  17. ^ a b Cite error: The named reference NYT-20141107-KC was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference JPL141107 was invoked but never defined (see the help page).