333P/LINEAR

333P/LINEAR is a Jupiter family periodic comet in retrograde orbit with an orbital period of 8.7 years. Upon discovery it was the sun-orbiting natural object in retrograde orbit with the shortest known orbital period. The comet was discovered by LINEAR on 4 November 2007.

When discovered on 4 November 2007, the comet had an apparent magnitude of 18.5–19 and was asteroidal in appearance. It was given the provisional designation. During the next apparition, it was recovered by the iTelescope Observatory, in Siding Spring, Australia, on 18 November 2015, when it had an apparent magnitude of around 20, and on 1 January 2016 by the SONEAR observatory. A small tail was observed and thus it was recategorised as a comet. It brightened rapidly and reached a magnitude of 12.6 on 28 March 2016.

When discovered, the comet was the first object with retrograde orbit within Jupiter's orbit. It was categorised as an Amor asteroid and was briefly considered potentially hazardous to Earth. Simulations indicated it was a comet nucleus that was possibly put into its current orbit after an interaction with Jupiter and in the future it will collide with the Sun or migrate beyond the orbit of Jupiter. The cometary activity has been found to play a role in the orbital evolution of the comet.