Video: Timelapse shows Comet ISON may have survived orbit around sun
TORONTO – It’s been one heck of a roller coaster ride.
As astronomers, both professional and amateur, tuned in to astronomy sites and blogs around the world on Thursday, it looked like the sun had killed Comet ISON.
READ MORE: ISON: What’s next?
However, much to the surprise of astronomers on Thursday — including those at NASA — around 4 p.m., EST images from NASA’s Solar and Heliospheric Observatory (SOHO) showed that something had survived the trip.
ISON, discovered in September 2012, had been touted as becoming the “comet of the century,” when it was calculated that it would pass very close to the sun, possibly creating a brilliant tail.
However, as it headed towards the sun, ISON wasn’t as brilliant as astronomers had hoped.
Though significantly dimmer and a lot less organized than the comet looked going towards the sun, it had become evident that part of the comet has remained intact.
There was the possibility, of course, that ISON is just was just its death throes.
Initially there was some speculation that what had come out the other side was just dust from the comet being torn apart. But as the hours passed, it became increasingly evident that what remained — though much smaller — was more than just dust.
Images and video clearly showed that some part of ISON remained and had brightened since its emergence.
As a comet passes through our solar system, the sun’s heat and solar wind causes frozen material to turn into gases in a process called sublimation, creating the tails of comets that we see.
The closer a comet gets to the sun, the more heat, thus more sublimation.
ISON’s tail stretched almost 16 million kilometres into space as it made its closest approach on Thursday.
But sun-grazing comets such as ISON run the risk of being torn apart by the sun’s intense gravity.
And that’s just what astronomers had thought had happened.
As ISON made its closest approach at 1:45 p.m. EST, it had lost its nucleus, or core. Many surmised that this signalled the end of the comet. Hope of its survival dwindled.
New images of ISON don’t show a distinctive nucleus, so it’s likely that it is merely a fragment of the two-kilometre wide comet that had approached the sun.
Astronomers around the world will continue to monitor the progress of ISON to see if it regains its brightness, though it’s likely that it will become dimmer or just fade from view entirely.
But if it continues to brighten, it will be visible in the early morning hours near the horizon within the next couple of days.
Stay tuned. Who knows what surprises await us with this mysterious and persistent comet.
Correction: An earlier version said ISON’s tail stretched for 8 million kilometres.