Comet ISON is on a track to come within 1 million miles from the Sun around 1:30 p.m., but scientists aren't able to predict what will happen next.

As of Nov. 27, images of the comet indicated that it would survive the encounter, but now scientists aren't so sure.

"It's going to get heated, it's going to get stressed by the solar gravity, many of us think it's going to break up into pieces, some people think it won't survive at all if it's too small. Other folks think it will come back out again," said Johns Hopkins University scientist Carey Lisse, during a NASA news conference.

NASA also said that people may be able to see the comet across "the pre-dawn sky" according to USA Today.

Lisse said ISON has around a 30-40 percent chance of surviving its solar orbit.

"The reason we study comet ISON to begin with is it's a relic," Lisse said. "It's a dinosaur bone of solar system formation. You need comets in order to build the planets. This comet has been in a deep freeze half way to the next star for the last four and a half billion years. It's just been coming in over the last few millions years and possibly even started around the dawn of man."

The comet is only three-quarters of a mile across and is packed with ice and dust, according to NASA.

If ISON falls apart before reaching the sun, it could still be visible if it splits into big pieces. Jim Green, director of NASA's planetary science division, confirmed that ISON's trip is likely "millions of years" in the making.

"It's a special comet," Green said. "It's probably the first time it's come in from a very long distance away - right at the edge of what our sun's gravity can hang on to. It may have taken millions of years to get to this location."

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