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Comet Lovejoy Plunges Into the Sun and Survives
boldie writes with a link to NASA's account of comet Lovejoy's close encounter with the sun. Excerpting: "This morning, an armada of spacecraft witnessed something that many experts thought impossible. Comet Lovejoy flew through the hot atmosphere of the sun and emerged intact. ... The comet's close encounter was recorded by at least five spacecraft: NASA's Solar Dynamics Observatory and twin STEREO probes, Europe's Proba2 microsatellite, and the ESA/NASA Solar and Heliospheric Observatory. The most dramatic footage so far comes from SDO, which saw the comet go in (movie) and then come back out again (movie)."
Here are larger QuickTime versions of the comet's entrance (22MB) and exit (26MB).
You realize that the sun doesn't actually have a surface, right? It's increasingly dense atmosphere all the way down.
Uh, the tail WAS blowing away from the sun. Take a look at the coronograph footage for a view that isn't wildly foreshortened:
For all but the most finicky of physics experiments, if we had pressure conditions of the density of the sun's corona, it would be "high vacuum." Very little conduction of heat from the plasma to a comet is going to take place. The bombardment by solar photons and the gigantic magnetic and gravitational fields of the sun play a greater role here than the actual material of the sun, and thus NASA can be pleasantly surprised by Comet Lovejoy's survival of its close encounter. But it's the wrong idea to picture this comet plunging into some sort of molten inferno. Of course, the sun's core is another story. 15 times denser than lead and 16 million kelvin. I'll like to see the comet that survives that.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
This is true to a small extent, but there's a feedback loop where the star gets bigger and cooler if the fusion rate increases. This results in (predominantly) only one element being fused at a time, so you have Hydrogen->Helium (with some slightly heavier elements, C,N, and O can be involved) until the star is almost out of hydrogen, then Helium->Things between LIthium and Oxygen, and after that the star goes boom pretty quickly (or lacks the mass to go any further).
By comparison the amount of fusion of elements heavier than the one it is burning at the time is extremely small.
The majority of all stars (such as our own) are burning Hydrogen.
The majority of all heavy elements come from supernovae (the stars that our sun was made of before it became a star again).
That being said, there is probably a large chunk of iron and other heavy elements (from past supernovae) in the middle of our sun, but we generally ignore it because it is such a small percentage.
It may end the earth as we know it!
Man, everything ends the earth as we know it.
I could go out there and shit in the bushes and BAM, the earth as you knew it where that bush was shit free? GONE.
btw, don't go out to your bushes for another few minutes. Bring toilet paper.
The effect we're discussing is easily observable to anyone who's reasonably familiar with a kitchen.
Ever fry french fries in oil? This is typically what? 350F?
Baking a pizza will typically be around 450F.
Yet it's easy to reach into a 450 degree oven and remove the pizza. As long as you use a towel or a tool, your hand can be in the same environment that just cooked the pizza for a relatively long time..
But any fool knows that reaching into the oil with your bare hand *at all* will burn your skin in less than a second. Even though the oil is 100 degrees cooler than the oven.
It's just a dramatic, every-day example of the difference in heat transfer between mediums (in this case, oil vs air).
Touch everywhere, even when inappropriate.