Discovered byGrigory Nikolaevich Neujmin
Discovery dateSeptember 3, 1913
1913 III; 1931 I; 1948 XIII;
1966 VI; 1984 XIX
Orbital characteristics
EpochMarch 6, 2006
Aphelion12.27 AU
Perihelion1.551 AU
Semi-major axis6.911 AU
Orbital period18.17 yr
18y 4m 12d (perihelion to perihelion)
Last perihelionMarch 11, 2021[1][2]
December 27, 2002[1][2]
Next perihelion2039-Jul-23[3][4]
Earth MOID0.55 AU (82 million km; 210 LD)
Physical characteristics
Dimensions21.4 km[5]
12.75 ± 0.03 hours[6]

28P/Neujmin, also known as Neujmin 1, is a large periodic comet in the Solar System. With a perihelion distance (closest approach to the Sun) of 1.5AU,[5] this comet does not make close approaches to the Earth.[5]

The comet nucleus is estimated to be 21.4 kilometers in diameter with a low albedo of 0.025.[5] Since 28P has such a large nucleus, it became brighter than the 20th magnitude in early 2019, roughly 2 years before coming to perihelion. When it came to opposition in May 2020, when it was still 3.5 AU from the Sun, it had an apparent magnitude around 16.9. But during the 2021 perihelion passage the comet was on the opposite side of the Sun as the Earth. The comet is not known for bright outbursts of activity.


  1. ^ a b Seiichi Yoshida (2004-09-07). "28P/Neujmin 1". Seiichi Yoshida's Comet Catalog. Retrieved 2010-02-26.
  2. ^ a b Syuichi Nakano (2001-05-01). "28P/Neujmin 1 (NK 798)". OAA Computing and Minor Planet Sections. Retrieved 2010-02-26.
  3. ^ "28P/Neujmin Orbit". Minor Planet Center. Retrieved 2021-09-12.
  4. ^ "Horizons Batch for 28P/Neujmin 1 (90000386) on 2039-Jul-23" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2023-05-02. (JPL#74/Soln.date: 2023-Mar-29)
  5. ^ a b c d "JPL Small-Body Database Browser: 28P/Neujmin 1" (last observation: 2023-03-21). Jet Propulsion Laboratory. Retrieved 2010-02-25.
  6. ^ Delahodde, C. E.; Meech, K. J.; Hainaut, O. R.; Dotto, E. (September 2001). "Detailed phase function of comet 28P/Neujmin 1". Astronomy & Astrophysics. 376 (2): 672–685. Bibcode:2001A&A...376..672D. doi:10.1051/0004-6361:20011028.