28P/Neujmin

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]

28P/Neujmin

Discovery
Discovered by	Grigory Nikolaevich Neujmin
Discovery date	September 3, 1913
Designations
Alternative designations	1913 III; 1931 I; 1948 XIII; 1966 VI; 1984 XIX
Orbital characteristics
Epoch	March 6, 2006
Aphelion	12.27 AU
Perihelion	1.551 AU
Semi-major axis	6.911 AU
Eccentricity	0.7755
Orbital period	18.17 yr 18y 4m 12d (perihelion to perihelion)
Inclination	14.2514°
Last perihelion	March 11, 2021[1][2] December 27, 2002[1][2]
Next perihelion	2039-Jul-23[3][4]
Earth MOID	0.55 AU (82 million km; 210 LD)
Physical characteristics
Dimensions	21.4 km[5]
Synodic rotation period	12.75 ± 0.03 hours[6]

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.