322P/SOHO is the first periodic comet to be discovered using the automated telescopes of the Solar and Heliospheric Observatory (SOHO) spacecraft, and second to be given a numbered designation, after 321P/SOHO. At perihelion, it is six times closer to the Sun than the planet Mercury.
Observational history The comet was first spotted by Terry Lovejoy after analyzing SOHO imagery on 4 September 1999.
After Kazimieras Černis spotted another SOHO comet in 2003, Sebastian F. Hönig, later determined that both P/1999 R1 and P/2003 R5 might be the same object, where he predicted its return in 2007. His calculations were later proven correct when it was successfully recovered by Bo Zhou as P/2007 R5 after analyzing SOHO images on 10 September 2007. It became one of the first comets that SOHO has discovered that is confirmed to be periodic.
Bo Zhou recovered the comet once again on 6 September 2011. It was observed again in September 2019.The case of the Sun-diving asteroid that thinks it's a comet Phil Plait, September 4, 2019
Possible connection with the Great Comet of 254 AD It has been suggested that 322P/SOHO is associated with a comet observed in November–December 254 AD and is mentioned in East Asian sources to have an extremely long tail. If the association is correct, it is possible that the comet split in 254 AD, resulting in intense cometary activity, but activity decreased afterwards as the comet lost most of its volatiles, and no longer displays a tail or a prominent coma. Current activity is fueled by sodium sublimation.
Physical characteristics 322P/SOHO is either an extinct comet or an active asteroid. Light-curve and infrared observations by Spitzer in 2016 suggest that its nucleus is probably only in diameter, with a rotation period lasting hours.
Orbit Perihelion distanceat different epochs Periheliondate Perihelion(AU) 1955-04-18 0.0651 1983-08-08 0.0597 1999-09-05 0.0563 2015-09-04 0.0535 2019-08-31 0.0506 2023-08-21 0.0501 2027-08-11 0.0505 2031-08-01 0.0479 2047-05-23 0.0451
322P/SOHO is a member of the Kracht sungrazer family of comets. On 11 April 1947, it passed about from Earth.
Exploration On 2 September 2019, NASA's Parker Solar Probe incidentally passed the tail of 322P/SOHO at a distance of , making direct measurements of the comet as it interacted with the solar wind.
See also List of minor planets and comets visited by spacecraft
References RNG_3sigma = uncertainty range in km. (JPL#10/Soln.date: 2016-Oct-27)
(JPL#10/Soln.date: 2016-Oct-27)
External links
SOHO's first officially periodic comet 322P/SOHO at Seiichi Yoshida's website 322P/SOHO at Gideon van Buitenen's website SOHO Comets (view real-time images)