As Comet ISON races towards the sun, scientists are watching to see if it will survive the journey to become a bright and beautiful feature in the northern skies, or if its 5,5-million year journey will end with it being pulled apart.

The comet will pass within 730 000 miles (1,17-million kilometres) of the sun tomorrow (28 November). NASA’s Solar Terrestrial Relations Observatory (STEREO) is monitoring its movements.

Don Yeomans, a senior research scientist at JPL, heads a group charged by NASA to watch for objects whose orbits bring them close to Earth. He says the world’s interest in Comet ISON is for a number of reasons:
“First of all, it’s coming from the very edge of our solar system so it still retains the primordial ices from which it formed four-and-a-half billion years ago,” he says.

“It’s been travelling from the outer edge of the solar system for about 5,5-million years to reach us in the inner solar system, and it’s going to make an extremely close approach to the sun and hence could become very bright and possibly a very easy naked-eye object in early December.”

There are three possible outcomes tomorrow, when Comet ISON rounds the sun, he says.

“It could be tough enough to survive the passage of the sun and be a fairly bright naked-eye object in the early morning sky in the first week of December.

“Or, the sun could actually pull it apart. The tidal forces could actually pull this comet apart and so it becomes several chunks rounding the sun and putting on a great show again in early December.

“Or, if the comet is very weak, it could break up into a cloud of dust and be a complete bust in December.”

* You can see a video of the comet approaching the sun here: