Video Transcript: Comet ISON Dazzle or Dust?
Don Yeomans: There's great interest in Comet ISON for a couple 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. It's been traveling from the outer edge of the solar system for about five and a half million years to reach us in the inner solar system, and its 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's three possibilities when this comet rounds the sun on Thanksgiving Day 2013. 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 has several chunks rounding the sun and putting on a great show again in early December. Or, if the comet's very weak, it could break up into a cloud of dust and be a complete bust in December.
Well, Comet ISON shouldn't be feared. It should be appreciated for the opportunities it's going to present. It's going to round the sun on Thanksgiving Day and there's going to be a small army of amateur and professional astronomers on the Earth, and spacecraft are going to be observing this object near the sun. So we're going to find out a great deal about what this comet is made of and hence were going to find out a great deal about what the solar system was like four and a half billion years ago.