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Last updated on April 24, 2014 at 16:36 EDT

Comet ISON Shows Signs Of Life After Close Encounter With Sun

November 29, 2013
Image Credit: ISON appears as a white smear heading up and away from the sun. ISON was not visible during its closest approach to the sun, so many scientists thought it had disintegrated, but images like this one from the ESA/NASA Solar and Heliospheric Observatory suggest that a small nucleus may be intact. Credit: ESA/NASA/SOHO/GSFC

Lawrence LeBlond for redOrbit.com – Your Universe Online

Last night astronomers were putting the final nail in the coffin for Comet ISON, which had been streaking toward its close encounter with the sun for months, culminating with a perihelion (closest approach of the sun) on Thanksgiving Day.

Described as the “comet of the century” by some and predicted to just “fizzle out” by others, ISON has been a hot topic since it was first discovered by Russian astronomers on September 21, 2012.

While many were gearing up for what could be a spectacular show as the frozen chunk of gas made its way past the sun yesterday afternoon, it later became evident that the comet was on a one-way trip toward obliteration.

Or was it?

As the comet sailed past our solar neighbor late yesterday, astronomers monitoring the comet’s progress declared that it was unlikely that the cosmic visitor survived its encounter with the sun.

“At this point, I do suspect that the comet has broken up and died,” Karl Battams, a comet scientist with the Naval Research Laboratory, said last night during a NASA and Google+ chat from Arizona’s Kitt Peak Observatory, according to a USA Today report yesterday. “Let’s at least give it a couple of more hours before we start writing the obituary.”

However, Battams now believes that some parts of ISON’s nucleus survived perihelion.

“It now looks like some chunk of ISON’s nucleus has indeed made it through the solar corona, and re-emerged,” he said in an interview with CNN’s Amanda Barnett. “It’s throwing off dust and (probably) gas, but we don’t know how long it can sustain that.”

[ Watch the Video: ISON Survives ]

While this is definitely good news for astronomers, it’s far from great news for the comet.

“Now it has emerged and started to brighten, we need to observe it for a few days to get a feel for its behavior,” Battams noted.

It is possible that it still may not survive its harrowing ordeal.

A trove of spacecraft eyed ISON as it made its way toward the sun. These include NASA’s STEREO satellite, the ESA/NASA SOHO spacecraft and the Solar Dynamics Observatory (SDO).

As ISON appeared to fizzle on its solar approach, coming as close as 730,000 miles from the fiery behemoth, NASA’s SDO and ground-based observatories lost sight of it completely and many experts believed that the comet had disintegrated entirely on its approach.

However, by late evening things began to brighten up a bit. Mr. Battams, writing in his blog as part of NASA’s Comet ISON Observing Campaign (CIOC), had the following to say:

“As comet ISON plunged towards to the Sun, it began to fall apart, losing not giant fragments but at least a lot of reasonably sized chunks. There’s evidence of very large dust in the form of that long thin tail we saw in the LASCO C2 images. Then, as ISON plunged through the corona, it continued to fall apart and vaporize, and lost its coma and tail completely just like Lovejoy did in 2011. (We have our theories as to why it didn’t show up in the SDO images but that’s not our story to tell – the SDO team will do that.) Then, what emerged from the Sun was a small but perhaps somewhat coherent nucleus, that has resumed emitting dust and gas for at least the time being. In essence, the tail is growing back, as Lovejoy’s did.”

He continued, “So while our theory certainly has holes, right now it does appear that a least some small fraction of ISON has remained in one piece and is actively releasing material. We have no idea how big this nucleus is, if there is indeed one. If there is a nucleus, it is still too soon to tell how long it will survive. If it does survive for more than a few days, it is too soon to tell if the comet will be visible in the night sky. If it is visible in the night sky, it is too soon to say how bright it will be…”

ISON, officially named C/2012 SI, was 585 million miles away when it was discovered by astronomers Vitali Nevski and Artyom Novichonok. The comet’s journey through the solar system has been an amazing adventure chronicled by amateur and professional astronomers for more than a year.

“From the beginning, ISON has confused, surprised and amazed us, and in hindsight its latest little escapade really should not shock us,” Battams told CNN. “Nonetheless, this has been one of the most extraordinary comets we have ever encountered, and just goes to reiterate how beautiful, dynamic and exciting our universe is.”

By the end of the NASA/Google Hangout, it was pretty much assumed that ISON was a dead stick. But astronomers on both fronts – pro and am – were undeterred and continued to monitor the heavens for any signs of ISON’s appearance from behind the sun.

Images from the NASA/ESA SOHO spacecraft clearly showed that something was emerging from behind the sun. Now that there are signs of life, it will still take some time to determine if the comet is in fact alive and well.

“We have a whole new set of unknowns, and this ridiculous, crazy, dynamic and unpredictable object continues to amaze, astound and confuse us to no end. We ask that you please be patient with us for a couple of days as we analyze the data and try to work out what is happening,” said Battams on his blog.

If anything, it looks as if there is still more to come and ISON may in fact still be ready to prove it is the “comet of the century” and hasn’t just “fizzled out.”


Source: Lawrence LeBlond for redOrbit.com - Your Universe Online