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Descent of the Sungrazer

Comet ISON is heading for the sun

If you haven’t looked for Comet ISON yet, now is the time. In just the past few days, the comet has grown more than 15 times brighter and is now visible to the unaided eye low in the east-southeast before dawn.
    These are the final days before ISON passes behind the sun, coming within 730,000 miles of its fiery surface November 27. Will the heat tear asunder this sun-grazer? Or will it survive and grow brighter as some of its matter is boiled into more reflective vapor? No one knows, and we won’t until early December when ISON reemerges from behind the sun — or doesn’t.
    But you don’t want to wait to see ISON. At week’s end, it crests the east-southeast horizon around 6am, and there are several other bright objects to guide you to it. You should have no trouble finding the blue-white star Spica a dozen degrees above ISON. Even brighter Mercury is just a few degrees to the east with Saturn fast on its heels. Then over the following days, ISON rises a few minutes later as it nears the rising sun, but as it does it grows all the brighter.
    Like all comets, ISON was formed in the infancy of the solar system from the coalescing cosmic gas and dust. In all those eons, this is the first time ISON has visited the inner solar system. Its icy body is pristine, never having been heated by the sun, so astronomers are anxious to study its composition from the gases it releases as the sun boils off its surface or even vaporizes the entire object.
    While you’re tracking ISON, you’ll witness the close conjunction of Mercury and Saturn in the early-morning skies Monday when the two planets come within one degree of one another. Mercury, the much brighter of the two, is sinking fast, while golden Saturn is just climbing into view. And while both are easily bright enough to see with the naked eye, binoculars will help pick them out from the glare along the horizon.