They’re calling it the Thanksgiving comet. Could Comet ISON be the comet of the century? Since it was discovered by a pair of Russian amateur astronomers using the International Scientific Optical Network (ISON) in 2012, inquiring eyes have been on Comet ISON. If the comet survives its close encounter with the sun (perihelion) on November 28th, we could see an awesome sky show in early December.
ISON would be closest to Earth on December 26, passing by on its way back out to the outer regions of the solar system. For weeks, the comet could be visible all night long, and bright as Venus in daylight!
You can follow the progress of Comet ISON and see some of the amazing pictures all over the internet. Space.com and NASA are very good. ISON has been an impressive sight, brightening as it rushes toward the sun.
Sungrazing comets are not uncommon. Comet Lovejoy in 2011 was a sungrazer, and it became a beautiful comet. But something like ISON has never happened before! Its size and hyperbolic trajectory suggests this is its first appearance from the outer regions of the Oort Cloud into the inner solar system.
The Oort Cloud is way out beyond the orbit of Neptune. It is made up of billions of orbiting icy bodies believed to be fragments from the formation of the solar system. Occasionally, there is a disturbance in the Oort Cloud, causing one of these bodies to fall into the inner solar system as a long-period comet.
ISON has been making this journey toward the sun for over 3 million years.
Periodic comets (Halley’s Comet, for example) have elliptical orbits; they come around again and again, making regular swings through the solar system. Oort cloud comets like ISON have such extreme trajectories, it’s a one-time trip. They head back out into the black, never seen again.
At perihelion, the comet will be traveling at 248 miles per second, encountering solar temperatures of up to 5,000 degrees Fahrenheit!
Will ISON survive? Keep up on the latest updates, and cheer on the comet at EarthSky.
Whether ISON remains intact, breaks up, or is completely destroyed during its encounter with the sun, for scientists, it has provided a rare opportunity to gather information about the chemical composition of primordial comets and the formation of the solar system. There will be plenty of data to study for years to come.
Whatever happens, it’s going to be something to see.
I watched the fragments of Comet Shoemaker-Levy-9 falling into Jupiter in 1994 on TV. ( There are videos on YouTube.) The images are astonishing, still. It was the first observation of a collision in the solar system. It was also an early example of the possibilities of the internet, as reports came in from observation sites around the world.
I will always remember Comet Hyakutake, in March of 1996. Harry and I could see it even without binoculars from our own backyard. It was a magnificent sight. They call it the Great Comet of 1996.
Will Comet ISON be one of the great ones?
UPDATE —As of 1:11 PM Thanksgiving Day, reports of ISON breaking up…
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