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(meteorobs) NAKED EYE COMET FOR NEXT CHRISTMAS?

Something to look forward to a year from now?  We'll see . . . 

A NAKED EYE COMET FOR CHRISTMAS 2001?

 From http://meteors.com/cometlinear/an_18th_magnitude.html

 An 18th magnitude "asteroid" first detected by the LINEAR Telescope on
 November 16th, but later shown to be a distant comet, could become a naked
 eye object in November and December 2001. An estimate based on its current
 brightness suggests that it could reach about magnitude 4.5 by late November
 2001, but could do better if it is a new comet and brightens rapidly
 initially.

 The object, designated 2000 WM1, was at about 6AU (900 million kilometres)
 from the Sun - well beyond the orbit of Jupiter - when discovered. With a
 full month of observations available to calculate the comet's orbit it
 should show very little change even as new data arrive. The comet, now named
 Comet C/2000 WM1 (LINEAR), will reach perihelion around 18:30UT on January
 22nd 2002, at 0.555AU (83 million kilometres) from the Sun.

 Initially the comet will be a northern hemisphere object only. However, in
 early December 2001 it will pass quite close to the Earth (0.32AU, or 49
 million kilometres) and, around this time will cross rapidly to the southern
 hemisphere. At the time of closest approach it will be close to opposition
 and visible almost all night.

 An estimate of its brightness suggests that it is of about average size -
 perhaps 3km in diameter -and that its average magnitude, that is, the
 brightness that it would have if it were simultaneously 1AU (150 million
 kilometres) from the Sun and the Earth, is 6.5. This is 10 times fainter
 than Comet Halley and nearly 1000 times fainter than Comet Hale-Bopp, but
 comparable with 19961s beautiful Comet Hyakutake.

 If it were to behave like an average comet, it might be expected to reach
 magnitude 4.6 by mid-December 2001. This is bright enough to be easily
 visible to the naked-eye from a dark site. However, if it is a new comet and
 brightens rapidly initially, it could even be significantly better than
 this. A new comet often has a layer of very volatile carbon monoxide ice on
 the surface of its nucleus. This ice coating sublimes violently at a large
 distance from the Sun, making the comet brighten very rapidly - at least
 initially - although close to the Sun such comets "slow down" considerably.

 The comet should be visible continuously through perihelion as it recedes
 from the Earth, although it will only be visible from the southern
 hemisphere during January 2002. After perihelion it will move back north. At
 perihelion it may be as bright as magnitude 4.0, but will fade rapidly
 afterwards. During late December and early January 2001-2002 the comet will
 be almost side-on to the Earth, showing the maximum extent of its tail in
 the sky.

 Although no comet can be relied upon completely, there is a very good chance
 that Comet C/2000 WM1 (LINEAR) will be a naked-eye Christmas comet for 2001.


 Erich Landstrom, NASA JPL Solar System Educator
 Director of Astronomy Education, South Florida Science Museum
 Dr. Buzz Aldrin Planetarium and Henry C. Gibson, Sr. Observatory
 4801 Dreher Trail North, West Palm Beach, FL 33405
 HTTP://WWW.SFSM.ORG

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