I had heard that comet ISON might not survive a close pass by our Sun, and I was curious about the odds of how other comets had fared. So, how often do other comets survive a close pass by our sun? Also, are there any connections between a comet's size or buildup(of material) that makes it more or less likely to not survive?
- How close is perihelion? Too close and it may be destroyed on its first pass. We know Halley's Comet, which has a perihelion of about 0.6AU, has been orbiting for over 2000 years, passing the sun every 74-76 years and is still going strong.
- How big is it? Every pass loses material, so a bigger comet could last longer.
- What is its composition? Darker comets can absorb more energy when close to the sun, which may accelerate outgassing and breakup.
And of course some comets hit large objects - Shoemaker-Levy hit Jupiter and was destroyed.