(Named for Johann Franz Encke, who calculated its orbit in 1819)
The single most observed comet, Encke's Comet has been viewed for approximately 50 passes. Already possessing one of the shortest orbital periods (only 3.3 years), its period is further decreasing by up to 2.7 hours per revolution. This is presumed to be caused by an observed jet effect from the cometary nucleus, which is not thermically symmetrical. Nevertheless, in 165 years of observation, the brightness of Encke's Comet has hardly decreased at all.
Encke's Comet is thought to be the parent body of the Taurid meteor stream, an annually recurring minor meteor shower which culminates on November 8, and radiates from two perceived radiants: RA 56°, dec +14° and + 22°.
Because the orbit of Encke's Comet is so very well known, it is considered a prime target for an exploratory space probe to investigate.