13 December 2008 00:11
- bodies of ice, gas, dust, and rocks orbiting the sun
- as comets near the sun, material boils off and comets develop a coma, a gaseous ball, and a tail which stretches out behind the comet
- the word comet comes from Greek; Aristotle called them komētēs or "stars with hair"
- comets are described by their orbital period, those with periods of 200 years are less are considered short-period, and greater than 200 years are considered long-period
- some comets only swing by the sun once before being tossed out of the solar system like unruly drunks
- many comets are visible only through telescopes, about one a year is visible to the naked eye
- comets used to be described by the year of their appearance, then they were named for their discoverer, today they are named for two or three independent discoverers and given a coded designation by the IAU
- sometimes comets brighten suddenly - as happened with Comet Holmes in 2007 pictured below
