Comet's crunch time
CAPE CANAVERAL, Fla. - For months, all eyes in the sky have pointed at the comet that's zooming toward a blisteringly close encounter with the sun.
The moment of truth comes Thursday - Thanksgiving Day.
The sun-grazing Comet ISON, now thought to be less than a mile wide, will either fry and shatter, victim of the sun's incredible power, or endure and quite possibly put on one fabulous celestial show. Talk about an astronomical cliffhanger.
Even the smartest scientists are reluctant to lay odds.
Should it survive, ISON would be visible with the naked eye through December, at least from the Northern Hemisphere. Discernible at times in November with ordinary binoculars and occasionally even just the naked eye, it already has dazzled observers and is considered the most scrutinized comet ever by NASA. But the best is, potentially, yet to come.
Detected just over a year ago, the comet is passing through the inner solar system for the first time. Still fresh, this comet is thought to bear the pristine matter of the beginning of our solar system.
It's believed to be straight from the Oort cloud on the fringes of the solar system, home to countless icy bodies, most notably the frozen balls of dust and gas in orbit around the sun known as comets. For whatever reason, ISON was propelled out of this cloud and drawn toward the heart of the solar system by the sun's gravitational pull.
The closer the comet gets to the sun, the faster it gets. In January, it was clocked at 40,000 mph. By Thursday, with just a week to go, it had accelerated to 150,000 mph.
Right around the time many Americans will be feasting on turkey, the comet will zip within 730,000 miles of the sun. By the time ISON slingshots around the sun, it will be moving at 828,000 mph.
The comet will venture no closer to us than about 40 million miles, less than half the distance between Earth and the sun. That closest approach to Earth will occur Dec. 26. Then it will head away in the opposite direction forever, given its anticipated trajectory once it flies by the sun.
ISON is named after the International Scientific Optical Network, used by Russian astronomers to detect the comet in September 2012.
But it still isn't known "whether we'll see a comet, comet bits or the last wisps of comet vapor," acknowledged Nick Schneider, associate professor in astrophysical and planetary sciences at the University of Colorado. "Whatever happens, it's bound to be interesting. The quip from my colleagues is, 'Comets are like cats: They have tails and do whatever they want.'â"