January 19, 2013
Comet Of The Century Passing Through Sun’s Atmosphere In November
[ Watch the Video: ScienceCasts: Comet of the Century ]
redOrbit Staff & Wire Reports - Your Universe Online
Comet ISON, which was found by Vitali Nevski and Artyom Novichonok of Roscosmos and named in honor of their International Scientific Optical Network night-sky survey program, is currently located near Jupiter.
For now, at least, it appears to be “a faint speck of light” that is “moving through the black of space,” but as it approaches the sun in November, it could become quite a sight, says the US space agency.
“Comet ISON is a sungrazer,” Karl Battams of the Naval Research Laboratory (NRL) explained in a statement. “The orbit of the comet will bring it very close to the sun, which we know can be a spectacular thing.”
Currently, Comet ISON is only visible with large telescopes, but near the end of the year, it could become “a striking naked eye object visible even in broad daylight” due to its proximity to our sun, NASA officials said.
In fact, even now it is tremendously bright, despite its distance, and that quality suggests that it is giving off dust and gas from a nucleus that could be between one and ten kilometers in size, reports Matthew Knight of the Lowell Observatory in Flagstaff, Arizona.
Comet ISON will travel through the sun´s atmosphere on November 28, passing just over one million kilometers from the stellar surface. It may not survive, but if it does, it could appear as bright as the Moon in our night sky. It could even be visibly near the sun, in broad daylight, for a short amount of time — leading some reporters to dub ISON the “Comet of the Century,” according to the agency.
However, the moniker may be premature, NASA officials argue.
"I'm old enough to remember the last 'Comet of the Century'. It fizzled. Comets are notoriously unpredictable," said Don Yeomans of NASA Near-Earth Object Program. Yeomans is referring to the 1973 comet known as Kohoutek, which failed to live up to expectations similar to those now attached to ISON, and even wound up becoming a punch line for late night comedians such as Johnny Carson, according to NASA.
"Comet ISON has the potential to live up to the hype, but it also has the potential to do nothing," added Battams.
Solar radiation and tidal forces could destroy the comet, as happened to Comet Elenin when it approached the sun in 2011. Alternatively, Comet Lovejoy — which, while smaller than ISON, was closer in size to the current comet than the much tinier Elenin was — survived its journey through the sun´s atmosphere and emerged with a spectacular tail.
"Comet ISON is probably at least twice as big as Comet Lovejoy and will pass a bit farther from the sun´s surface,” Knight said. “This would seem to favor Comet ISON surviving and ultimately putting on a good show.”
The comet could also experience a partial split, which would make it look like “a string of pearls” when viewed using a telescope, Battams said. He added that, should such a phenomenon occur, ISON could wind up looking like “the famous Comet Shoemaker-Levy 9 that hit Jupiter in 1994.”
Should it break up entirely, there will be no threat to us here on Earth, assures Yeomans. The comet itself is not on a collision course with our planet, and any fragments resulting from its destruction would simply continue along the same, original trajectory ISON would have followed in its entirety.
“Whatever happens, northern sky watchers will get a good view,” NASA officials said. “For months after it swings by the sun, Comet ISON will be well placed for observers in the northern hemisphere. It will pass almost directly over the North Pole, making it a circumpolar object visible all night long.”