- Encke's comet
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/eng"keuhz, -keez/a comet, discovered by J.L. Pons, with a period of 3.3 years, the shortest period known.[named after Johann F. Encke (1791-1865), German astronomer]
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Faint comet having the shortest orbital period (about 3.3 years) of any known, first observed in 1786.It was the second comet (after Halley's Comet) to have its period determined (1819), by Johann Franz Encke (1791–1865). Encke also found that the comet's period decreases by about 212 hours in each revolution and showed that this effect could not be explained by the planets' gravitational influence. Its period continues to decrease, though more slowly, and appears to be related to the effects of outgassing.* * *
faint comet having the shortest orbital period (about 3.3 years) of any known; it was also only the second comet (after Halley's) to have its period established. The comet was first observed in 1786 by Pierre Méchain (Mechain, Pierre). Johann Franz Encke (Encke, Johann Franz) in 1819 calculated that sightings of apparently different comets in 1786, 1795, 1805, and 1818 were in fact appearances of the same comet, whose short orbital period he was able to deduce. The comet was named in his honour, though usually comets are named after their discoverers. Encke also found the comet's period to be decreasing by about 2 1/2 hours in each revolution and showed that this behaviour could not be explained by gravitational perturbations (slight changes in an orbit) caused by planets. The American astronomer Fred Whipple explained it in 1950 as the effect of jet forces produced by vaporization of the comet's nucleus in combination with the rotation of the nucleus.* * *
Universalium. 2010.
