ISON question

[Sal Manella]

If the comet ISON currently headed to pass EARTH and swing around the sun were to break up as it approaches the sun, Could that comet break up and literally shotgun the solar system as the pieces emerge from going around the sun ?

[geckzilla]

If the comet breaks apart, most of the pieces still remain in the same orbit. The orbit does not cross with Earth's if you were concerned about that. I watched this Hubble Hangout recently and they explained that we can't get a meteor shower because of this.

[thailazer]

It seems no one is certain what will happen as it passes something like a sun's diameter from the sun. I would think all the ice will be vaporized, causing all kinds of strange dynamics. This is one of the most exciting things to happen in astronomy in my lifetime and I am hoping for a good show as it emerges from the back side. I still remember Hale-Bopp being visible from the car window when I was driving home from work. Ison has the possibility of being much brighter, but it could also just be gas-less (and dull) debris field. At least we don't have to wait long to find out!

Anyone else have opinions on Comet Ison's chances in the close encounter with the sun?

[neufer]

Anyone else have opinions on Comet Ison's chances in the close encounter with the sun?

Comet ISON will only come 1.675 R_☉ of the Sun's photosphere at perihelion;
evaporative cooling should prevent Comet ISON from getting too hot on the surface.

[b][color=#0000FF]Image of Comet Shoemaker–Levy 9 fragments (total: 21)[/color][/b]

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Kreutz Sungrazers, are a family of comets which regularly pass safely within 1 R_☉ of the Sun's photosphere at perihelion.

Comet Shoemaker–Levy 9 broke apart from tidal forces but only by coming 0.57 R_J of Jupiter's clouds at perijove. It suffered about 5 times the tidal forces that Comet ISON must endure.

[thailazer]

Thanks for that neufer. That gives hope for a good show coming up. It is hard for me to conceive that evaporative cooling can last long enough that close to the sun, but the physics laws rule.

[Chris Peterson]

It seems no one is certain what will happen as it passes something like a sun's diameter from the sun. I would think all the ice will be vaporized, causing all kinds of strange dynamics.

The dynamics wouldn't be that strange. Orbital properties are determined by the distance of the body from the Sun; the body's mass isn't a factor. So at most, you have some perturbing forces created by escaping volatiles. But those forces are generally small, and for a rotating body, fairly isotropic. So while some orbital perturbation can reasonably be expected, the changes to the orbit should be small- for instance, a change in eccentricity or semi-major axis affecting the periodicity. The position of the body (or bodies, if there is a breakup) as it leaves the inner system should be pretty close to that given by the current orbital elements.

[neufer]

It is hard for me to conceive that evaporative cooling can last long enough that close to the sun, but the physics laws rule.

I figure that about one centimeter of ice per second needs to evaporate from the sun facing side for about an hour (for a loss of about 36 meters of ice).

This shouldn't be a problem for a nucleus larger than 500 meters.

[neufer]

Click to play embedded YouTube video.

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Snow balls in space