Editing 2060 Chiron (section)

=== Cometary behavior ===

In February 1988, at 12&nbsp;AU from the Sun, Chiron brightened by 75 percent.<ref name="hartmann1990" /> This is behavior typical of comets but not asteroids. Further observations in April 1989 showed that Chiron had developed a cometary [[coma (cometary)|coma]],<ref name="meech1989" /> A tail was detected in 1993.<ref name="Campins-1994" /> Chiron differs from other comets in that [[water]] is not a major component of its coma, because it is too far from the [[Sun]] for water to sublimate.<ref name="Meech90" /> In 1995 [[carbon monoxide]] was detected in Chiron in very small amounts, and the derived CO production rate was calculated to be sufficient to account for the observed coma.<ref name="womack1999" /> [[Cyanide]] was also detected in the spectrum of Chiron in 1991.<ref name="Bus91" /> At the time of its discovery, Chiron was close to aphelion, whereas the observations showing a coma were done closer to perihelion, perhaps explaining why no cometary behavior had been seen earlier. The fact that Chiron is still active probably means it has not been in its current orbit very long.<ref name="Perihelion" />

Chiron is officially designated as both a comet—95P/Chiron—and a minor planet,<ref name="dualstatus" /><ref name="Fornasier-2013" /> an indication of the sometimes fuzzy dividing line between the two classes of object. The term proto-comet has also been used. Being about 220&nbsp;km in diameter, it is unusually large for a [[comet nucleus]]. Chiron was the first member of a new family of [[Chiron-type comet]]s (CTC) with ([[Tisserand's parameter|T<sub>Jupiter</sub>]] > 3; [[Semi-major axis|a]] > a<sub>Jupiter</sub>).<ref name="jpldata" /> Other CTCs include: [[39P/Oterma]], [[165P/LINEAR]], [[166P/NEAT]], and [[167P/CINEOS]]. There are also non-centaur asteroids that are simultaneously classified as comets, such as [[4015 Wilson–Harrington]], [[7968 Elst–Pizarro]], and [[118401 LINEAR]].<ref name="dualstatus" />

Since the discovery of Chiron, other centaurs have been discovered, and nearly all are currently classified as minor planets, but are being observed for possible cometary behavior. [[60558 Echeclus]] has displayed a cometary coma and now also has the cometary designation 174P/Echeclus. After passing perihelion in early 2008, [[52872 Okyrhoe]] significantly brightened.<ref name="cometary" />