Comet Lovejoy Survives Fiery Plunge Through Sun
- Thread starter Ar-Pharazon
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The density of the corona is 9 orders of magnitude less than the Earth's atmosphere at 80 km altitude, or 14 orders of magnitude less than the atmosphere at sea level. I'd be more worried about the solar radiation.
^Good point. The figures on the temperature of the corona are misleading given its extremely low density; the individual particles have a lot of thermal energy, but relatively few of them would come into contact with the comet. The influx of light from the Sun would've been a far more important contributor of heat. At 140,000 km from the Sun -- about 1/1000 of an AU -- the insolation would've been about a million times more than we get at Earth, by the inverse square law.
Dunno, but it also lost its tail. (I believe some are expecting Lovejoy to sprout a new one, but I haven't seen any updates on that yet.)It started out about 660 feet wide. I wonder how much weight it lost
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See a time-lapse video clip of Lovejoy's trip past the Sun:
http://www.youtube.com/watch?v=STpAvrn74R0
Not surprising. Most of the volatiles probably got boiled/blown off in the close passage. What's left may be mostly rock.
Doesn't heat translate pretty poorly in space? I mean radiation isn't exactly the most effective form of energy transfer (as opposed to convection or conduction) so wasn't the comet "protected" by pretty much the fact the heat had no real, good, way to transfer to it?
Wow, did you see the sharp angle it took when it came out the other side? I bet that thing's gonna be slingshotted right out of the solar system!
Alex
My orbital mechanics are a bit rusty, but I don't think that's physically possible, not unless it was one half of a binary pair and the other half fell into the Sun or something. A space probe can gain velocity from a slingshot around a planet by stealing a fraction of the planet's own orbital momentum, but the Sun isn't orbiting itself, so there's no momentum to steal. Let's see, the comet would've accelerated under the pull of the Sun's gravity, but once it started heading outward again, that same gravity would start to decelerate it, like a ball tossed upward.
Current estimates are that it has an aphelion of about 92 AU and a period of 300-odd years. It will be back.
The sun seems to do a fine job helping to heat up our planet. Imagine the job it would do if we were 80,000 km away from it.
The comet was heated up to the point it was vaporizing. All of the less dense or more liquid materials on the comet were turned into gases. The solar "wind" at that altitude and at the speed the comet was travelling likely had a severe consequence too. There is probably only a small lump of ice/rock left, which is quite amazing.
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As FordSVT says, radiation is a perfectly workable method for transferring heat, and it's the way the Sun heats the Earth to livable temperatures and heats Mercury and Venus to unbearable temperatures. It's just not as good as conduction or convection. And it's dependent on how much heat a given body is radiating. A human body, say, won't freeze instantly in space as fiction would have it, because the rate at which it radiates energy outward is relatively low -- since it's simply not very hot, only about 310 K. Sol's surface temperature is nearly 20 times that, and its surface area is about 3 trillion times greater, so it's radiating 60 trillion times as much energy. So the fact that radiation is a somewhat less effective means of energy transfer is pretty thoroughly swamped by that. Sure, if you dumped the Sun and the Earth into a giant vat of water, the Earth would get heated up even more than it is already because of the improved heat transfer. But what we get is still plenty adequate. Everything's relative.
And of course, the heat from the Sun is what gives comets their tails in the first place -- enough energy is transferred to the comets to vaporize their volatiles (though it's then the solar wind that blows them out into long streaming tails). Eventually, after enough passages near the Sun, comets run out of volatiles and are reduced to asteroids, just rock and metal left over. The closer the passage, the more heat the comet takes in and the faster it outgases. But there's still going to be that rocky component left over once the volatiles are all gone.
Sooo... no time warp, then?
Story
Wow. A mostly (or all) ball of ice survives unbelievable temperatures.
It started out about 660 feet wide. I wonder how much weight it lost
Did they name it after lovejoy on the simpsons?
^No, it was named for its discoverer, Australian amateur astronomer Terry Lovejoy. His name is also appended to two other comets he's discovered (though they have catalog numbers as their official designations), and there's a Main Belt asteroid named for him too.
"It's not just the whales, it's the water!"
Has anyone seen this: Spectacular Photos: Astronaut Sees Dazzling Comet From Space Station
The comet looks spectacular from space.
The comet looks spectacular from space.
^ A few more to go with that one:
http://spaceflight1.nasa.gov/gallery/images/station/crew-30/inflight/ndxpage9.html
http://spaceflight1.nasa.gov/gallery/images/station/crew-30/inflight/ndxpage9.html
Hey, has the tail come back? If so, it might be worth getting up before dawn to see it.
When I was a kid, about eight or ten, my Dad too me outside to see, I think, Comet Bennett. It was spectacular, the tail about the length of five moons, when the moon just come up. Yeah, that big.
I'd like to experience that again
When I was a kid, about eight or ten, my Dad too me outside to see, I think, Comet Bennett. It was spectacular, the tail about the length of five moons, when the moon just come up. Yeah, that big.
I'd like to experience that again
I love it when the universe surprises and confounds the "experts".
Awesome story.
Awesome story.