C/2015 ER61 (PanSTARRS)

C/2015 ER61 (PanSTARRS)
Discovery
Discovered byPan-STARRS 1 (F51)
Discovery date15 March 2015
Orbital characteristics
Epoch7 May 2017 (JD 2457880.5)
Observation arc1.96 yr
Aphelion
  • 2456±62 AU
  • 1425/854 AU[1]
Perihelion1.0421 AU
Semi-major axis
  • 1229±31 AU
  • 715/428 AU[2]
Eccentricity0.99730
Orbital period
  • 7591 years[1]
  • 9000 years (epoch 2050)
Inclination6.3490°
235.21°
Argument of
periapsis		68.197°
Earth MOID0.1016 AU[2][3]
Mars MOID<0.00005 AU[3]
Jupiter MOID0.0794 AU[2][3]
Saturn MOID0.2869 AU[3]
Physical characteristics
Dimensions
~0.05 (assumed)
Comet total
magnitude (M1)
  • 20.5 (January 2016)
  • 14.74 (peak 1 May 2017)

C/2015 ER61 (PanSTARRS) is a comet and inner Oort cloud object. When classified as a minor planet, it had the fourth-largest aphelion of any known minor planet in the Solar System, after 2005 VX3, 2012 DR30, and 2013 BL76. It additionally had the most eccentric orbit of any known minor planet, with its distance from the Sun varying by about 99.9% during the course of its orbit, followed by 2005 VX3 with an eccentricity of 0.9973. On 30 January 2016, it was classified as a comet when it was 5.7 AU from the Sun.[5] It comes close to Jupiter, and a close approach in the past threw it on the distant orbit it is on now.

Though the comet nucleus was probably mildly active, early asteroidal estimates gave an absolute magnitude (H) of 12.3,[6] which would suggest a nucleus as large as 8–20 km in diameter. But it could easily be half that size due to activity brightening the nucleus.

  1. ^ Cite error: The named reference mpc 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).
  3. ^ a b c d Gray, Bill. "Find_Orb Orbit Determination Software". Project PLuto. Retrieved 22 April 2019.
  4. ^ "Glossary: Absolute Magnitude (H)". JPL. NASA. Archived from the original on 2 March 2001. Retrieved 14 September 2015.
  5. ^ Cite error: The named reference MPEC2016-C01 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference JPL13 was invoked but never defined (see the help page).