Comet ISON is teasing the solar system as it dances with the sun and it’s giving astronomers mixed signals.
Will it meet a fiery death or survive when it whips around the sun on Thursday?
The icy comet will be only about 1 million miles away from the sun’s super-hot surface during its close encounter on Thanksgiving. On Monday, it looked like it was about to die even before it got there. On Tuesday, it appeared healthy again.
“We have never seen a comet like this,” Naval Research Laboratory astrophysicist Karl Battams said during a Nasa news conference on Tuesday. “It has been behaving strangely.”
Because it is so close to the sun, ISON will likely not be visible from Earth on Thursday except via a fleet of Nasa telescopes and spacecraft aimed at the comet as it gets closest to the sun at 1-37 p.m. EST( (1837 GMT), he said. And it will be a few hours before scientists know whether the comet survives.
But even if the comet dies, Johns Hopkins University scientist Carey Lisse said there’s a good chance that people on Earth will get an interesting cosmic show. The comet’s remnants could paint the sky with a wide swath of green in the Northern Hemisphere.
Lisse gives the comet a 30 per cent chance of surviving, adding that it is just a gut-feeling that has little to do with logic. Logically, it should be 50-50, he said.
The comet two-thirds of a mile (about 1 km) wide is made up of loosely packed ice and dirt, essentially a dirty snowball. It is a “dinosaur bone,” from the formation of the solar system 4.5 billion years ago, Lisse said. It has been in “deep freeze” for billions of years in the Oort cloud, a vast area of comets and debris that never formed into planets that’s between 450 billion miles and 9 trillion miles from the sun, he said.
The comet is racing around the sun, pulled close by our star’s massive gravity, which can also break apart the dirty icy core. AP