back to article Thanksgiving ROAST in SPAAACE: Comet ISON faces FIERY SUN DEATH

On November 28, while many Americans will be sitting down to roast turkey and all the trimmings, Comet ISON faces being slowly cooked to death as it passes within a million miles of the Sun's surface. Now a top expert says the cosmic snowball has a less than fifty-fifty chance of surviving the encounter. "It's going to get …

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Mushroom

Hoping for a good show

I've been amused by all the comments I've seen around the web that are variations of "But won't the sun just burn it up?"

No it won't and for a few reasons. First ISON is big. I've heard estimates of between 1 km and 500 m. Second, it gets a bit of shielding from radiative heating by its coma. The coma is being pulled away by the solar wind, but it is still enough to slow the sun's heating. Third, while the sun's corona is very hot (hotter than its surface) it is also very thin. It's really a vacuum, just a slightly thicker vacuum than the vacuum that is out by Earth's orbit. Fourth, it's not going to be near the sun for very long. It's currently moving at 115 km/s and will be moving even faster on the 28th. It is currently 23 million km from the sun. It'll go past the sun by 750,000 km on the 28th. By the 30th it'll be 25 million km away from the sun (heading roughly towards us and north out of the ecliptic). In 4 days it will manage to cover almost 50 million km, which is roughly 1/3 of the distance from the Earth to the sun.

What might happen is either ISON comes through in one piece (admittedly smaller than it was) or tidal forces from the sun's gravity will cause it to break apart. If it does break up, it should have a larger tail than if it stayed in one piece. Comet Lovejoy (2011) for a quick comparison was only 500 m in diameter. At perihelion it was 5x closer to the sun and was moving at 500+ km/s. It survived intact and gave folks in the southern hemisphere a great show.

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Re: Hoping for a good show

Comets are like cats. They have tails and do whatever they want.

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Re: Hoping for a good show

Except change orbit and rip your sofa.

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So if Ison does end up getting roasted...

It will be a turkey of a comet?

(There was a pretty decent PBS/National Geographic Channel special on the comet last week. It might be available online at PBS.org if anyone is interested.)

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Intelligent design at Nasa?

"... it will have started falling towards the Sun more than a million years ago, well before mankind even came down from the trees... "

I think our ancestors left the trees a lot more then one million years ago...

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Re: Intelligent design at Nasa?

Was just coming here to post that myself. Depending on which subspecies you choose to include in the term "human", humans are between 8 and 6 million years old while hominids are at least 15 million years old.

We came out of the trees a hell of a lot longer than 1 million years ago.

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Re: Intelligent design at Nasa?

Maybe they were up in the trees watching all the comets?

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Re: Intelligent design at Nasa?

Yeah I am sure the biologists and anthropologists cringed at that statement and wished the author kept to writing solely about astrophysics. Jarring, inaccurate, and completely irrelevant to the topic at hand.

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Re: Intelligent design at Nasa?

"I think our ancestors left the trees a lot more then one million years ago..."

I return from time to time: http://www.hovnanian.com/images/treetrim.jpg

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Two views a day

5am and 7pm - getting up and coming home. Nice. Just have to hope that we don't get our usual 10/10 cloud cover here!

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Anonymous Coward

Time Zones Please?

Some of us are somewhere else on the planet!

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Re Since it was first spotted in September

September 2012 that is.

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