331P/Gibbs (P/2012 F5)
DiscovererA. R. Gibbs
(Mount Lemmon Survey)
Discovery date22 March 2012
Epoch4 February 2012 (JD 2455961.5)
Observation arc11.3 years
Obs148
Aphelion3.130 AU
Perihelion2.877 AU
Semimajor3.004 AU
Eccentricity0.042
Period5.21 years (1902 days)
Inclination9.740°
Asc node216.86°
Arg peri177.40°
Tjup3.229
Earth moid1.88 AU
Jupiter moid2.08 AU
Mean diameter1.77 km (1.10 mi)
Rotation3.24 ± 0.01 hours
M 112.3
M 215.4
Last p25 December 2025[1]
29 September 2020
Next p16 March 2031[2]

331P/Gibbs (P/2012 F5) is a small periodic Encke-type and rare main-belt comet, discovered by American amateur astronomer Alex Gibbs.[3]

Description

It is a rare type of comet called a main-belt comet. Although most comets come from the Oort cloud or the Kuiper belt, main-belt comets are instead members of the asteroid belt that have a coma and tail. As of 2016, it is one of only 15 known main-belt comets.[4]

Precovery observations of 331P/Gibbs in Sloan Digital Sky Survey data were found dating to August 2004, in which the object was visible as a regular asteroid. Further observations in 2014 by the Keck Observatory showed that the comet was fractured into 5 pieces and rotating rapidly, with a rotation period of only 3.2 hours. Due to the YORP effect, P/2012 F5 had begun to spin so quickly that, being a likely rubble pile, parts began to be thrown off, leaving a very long dust trail.[5] This is very similar to 311P/PANSTARRS, being the best-established cause for main-belt comets along with impacts between small asteroids (such as with 596 Scheila and 354P/LINEAR).

References

  1. ^
  2. ^ "Horizons Batch for 331P/Gibbs (90001305) on 2031-Mar-16" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2026-04-19. (JPL#41 Soln.date: 2025-Dec-18)
  3. ^ "JPL Small-Body Database Browser: (331P/Gibbs)" (last observation: 2015-12-14)
  4. ^ "JPL Small-Body Database Search Engine". Jet Propulsion Laboratory. NASA. Retrieved 10 December 2016.
  5. ^ "Active asteroid spun so fast that it exploded". Astronomy Now. Retrieved 10 December 2016.