By Gary A. Becker
StarWatch 892 for the week of Sept. 22, 2013
Potentially one of the great comets of the last 50 years, ISON, is now headed sunward for a close encounter with Sol on Thanksgiving Day.
The big question is, “Will Comet ISON make it past the sun or will Sol simply cause it to go POOF?
Comets are loose aggregates of mainly ice (water) and dust and look similar to a dingy snow pile on a mall parking lot that’s been exposed to traffic for several weeks. Jab it with a snow shovel and it seems impenetrable; but pit it against the blistering heat and gravity of the sun and the comet’s rigidity becomes more like cotton candy.
Currently, Comet ISON is a Southern Hemispheric object with a tail of about two degrees and still only visible through larger telescopes.
Astronomers predict that ISON will peak at about the brightness of Venus on Thanksgiving as it passes within 700,000 miles of the sun’s photosphere (visible edge) and gets cooked to temperatures of nearly 5000 degrees F.
If the comet survives its solar passage on Nov. 28, ISON will rapidly move northward by the first week in December as an easily seen morning object with an impressive tail.
By December’s third week, ISON will become visible in the evening as well as the morning sky; and finally after Christmas, it will be seen all night long, that is unless Comet ISON becomes “lost in space” by the sun’s powerful forces. Optimistically, this year will end with a beautiful comet gracing our Yule sky.