|Discovered by||Terry Lovejoy, Kazimieras Cernis, Bo Zhou, and Sebastian Hönig|
|Discovery date||September 4, 1999|
|P/1999 R1, P/2003 R5, P/2007 R5, P/2011 R4|
|Orbital characteristics A|
|Epoch||2013-Jan-01 (JD 2456293.5)|
|Observation arc||16 years|
|# of observations used||299|
|Semi-major axis||2.5158179 AU|
|Orbital period||3.99 yr|
|19.00 ± 0.09|
|Last perihelion||September 7, 2011
September 11, 2007
Comet 322P/SOHO, also designated P/1999 R1, P/2003 R5, P/2007 R5, and P/2011 R4, is the first periodic comet to be discovered using the automated telescopes of the SOHO (SOlar and Heliospheric Observatory) spacecraft, and second to be given a numbered designation, after 321P/SOHO.
The periodicity of P/2007 R5 was predicted by Sebastian F. Hönig, a German graduate student and prolific asteroid discoverer, in 2006. The announcement of the new periodic comet was made after the predicted return was confirmed by SOHO and observer B. Zhou on 10 September 2007. Out of approximately 1,350 SOHO-observed sungrazer comets, this is the first to be verified as a short-period comet; most sungrazers are long-period comets on near-parabolic orbits that do not repeat for thousands of years, if at all.
P/2007 R5 is probably an extinct comet. Extinct comets are those that have expelled most of their volatile ice and have little left to form a tail or coma. They are theorized to be common objects amongst the celestial bodies orbiting close to the Sun. P/2007 R5 (SOHO) is probably only 100–200 meters in diameter.
- Jaggard, Victoria (2007-09-25). "Photo in the News: Sun Probe Spies New Periodic Comet". National Geographic News. National Geographic Society. Retrieved 2007-09-25.
- Marsden, Brian (18 September 2007), "MPEC 2007-S16 : COMET P/1999 R1 = 2003 R5 = 2007 R5 (SOHO)", Minor Planet Electronic Circular (2007-S16)
- "SOHO's new catch: its first officially periodic comet". European Space Agency. 25 September 2007. Retrieved 2007-11-19.
- Rainer Kracht (2011-09-07). "Recent comet discoveries 2123-2137". Yahoo Groups: SOHO Hunter. Retrieved 2011-09-11.
- Karl Battams (Jan 30, 2012). "The tale of a very shy comet...". Sungrazing Comets @ Navy.mil. Retrieved 2012-01-30.