Comet ISON Dances near the Sun

In this photo provided by NASA, a contrast-enhanced image produced from the Hubble images of comet ISON taken April 23, 2013 reveals the subtle structure in the inner coma of the comet. 

In this computer-processed view, the Hubble image has been divided by a computer model coma that decreases in brightness proportionally to the distance from the nucleus, as expected for a comet that is producing dust uniformly over its surface. 

ISON's coma shows enhanced dust particle release on the sunward-facing side of the comet's nucleus, the small, solid body at the core of the comet. 

This information is invaluable for determining the comet's shape, evolution, and spin of the solid nucleus. (AP Photo/NASA)

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 ( 1.6 million kilometers) away from the sun's super-hot surface during its close encounter on US Thanksgiving day.

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 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.