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 Tuesday. "It has been behaving strangely."
Because it is so close to the sun, ISON (EYE'-sahn) 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, he said. And it will
be a few hours before scientists know whether the comet
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
Lisse gives the comet a 30 percent 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 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
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
Comet ISON was first spotted by a Russian telescope in
September last year. While many comets come out of the Oort
cloud and return after a long trip through the solar system and
many comets graze by the sun, this is the first one that
astronomers have watched that is from the Oort cloud and is
skimming the sun.
Lisse said ISON could behave just like
last year's comet Lovejoy, which fell apart a couple days after
passing by the sun. Its remnants were visible like "a beautiful
paintbrush swath in the sky" in the Southern Hemisphere, he