|Discovery date||August 10, 2004|
|Orbital characteristics A|
(outside Saturn's orbit)
|Semi-major axis||16.28 AU|
|Orbital period||65.67 yr|
|Max. orbital speed||9.8 km/s|
|Min. orbital speed||5.6 km/s (2033-Nov-30)|
|Last perihelion||April 24, 2001|
167P/CINEOS (P/2004 PY42) is a large periodic comet and active, grey centaur, approximately 66 kilometers (41 miles) in diameter, orbiting the Sun outside the orbit of Saturn in the Solar System. It was discovered on August 10, 2004, by astronomers with the CINEOS survey at Gran Sasso in Italy. It is one of only a handful known Chiron-type comets.
The comet nucleus (~66 km) is roughly half the size of C/2014 UN271 (Bernardinelli–Bernstein) and it has a similar perihelion point just outside the orbit of Saturn.
|95P/Chiron||215 km||8.5 AU|
|C/2014 UN271 (Bernardinelli–Bernstein)||120 km||10.95 AU|
|167P/CINEOS||66 km||11.77 AU|
Due to its high Jupiter tisserand of 3.5, and a semi-major axis larger than that of Jupiter, 167P/CINEOS is classified as a Chiron-type comet, named after the groups namesake, 2060 Chiron or 95P/Chiron, designated as both minor planet and comet.
167P/CINEOS was first reported as a minor planet, designated 2004 PY42, but was found to have a very faint asymmetric cometary coma. Contrary to Chiron, which is the prototype object for the dynamical group of centaurs, 167P/CINEOS has no "dual status" as comet and minor planet, and demonstrates the inconsistencies in applying the current rules for designating small Solar System bodies. 167P/CINEOS not only has orbital parameters similar to those of Chiron, but also a low B–R magnitude of 1.29±0.03, which places it into the group grey centaurs.
In June 2039, 167P/CINEOS will pass 1.64 AU from Uranus.