…in what proximity would you have to be to the sun and how fast would you have to be spinning (like a rotisserie chicken) so that your light side didn’t burn and your dark side didn’t freeze; rotating just enough to keep a relatively stable temperature?
Absolutely absurd, I know but this question somehow popped into my head and won’t leave. 😆🐔🔥🧊
A wizard drops you on the moon. You immediately panic about not being able to breathe, plus your salivia is boiling and your blood is…well, it killed you pretty darn quickly.
Thankfully, the wizard noticed and set spells that puts a tiny bit of atmosphere right over your head, and , repairs the damage inflicted already. There is a chair and a go-board in front of you.
“Wait, that’s it?” you ask the wizard after he explains what the spells did. “Arent I going to burn, or freeze, or something?”
“Eventually, yeah,” says the wizard as he sits down. “But the human body’s great at homeostasis. Since your blood isn’t boiling it can circulate heat within you, you can burn calories to add heat as needed, and sweating is absurdly effective since the relative humidity of a vacuum is pretty much less than zero.”
“But, didn’t the Apollo capsule spin to manage heat, and aren’t there huge radiator fins on the ISS so they don’t slowly burn? I thought managing heat was hard?”
“It is. For an inanimate object. Especially one that isn’t filled with water or surrounded by a thermo exchange medium. You ever see a capsule bleed or a probe sweat?”
Outside of all the assumptions to make this work, the real issue is that the “dark side” doesn’t cool you like you’re thinking. Getting rid of heat in space is actually a hard problem to solve as a vacuum is a great insulator. Heat has to be radiated away, and that takes time and lots of surface area.
Interesting and does make sense. Where does this image of stuff freezing instantly as it “enters” space vacuum come from?
Moisture as any other fluid when exposed to vacuum of space expands and boils this transforms to vapour and that process absorbs energy which could cause the freezing.
Probably significantly further away than the earth’s orbit, given that (1) you can die of heatstroke from exposure to the sun at earth’s surface, and that’s with miles of air still absorbing much of the radiation; and (2) in the vacuum of space, there would be no air or other substances to conduct away your body heat, so you’d have to rely solely on radiative heat to cool off.
So even though its minus hundreds of degrees, your skin wouldn’t freeze instantly on your dark side in this situation?
It’s not minus hundreds of degrees, it’s body temperature. Vacuum has no temperature, and it’s an insulator, not a conductor.
That makes perfect sense to me on paper. It still makes my head spin thinking about though lol
I think part of the unintuitiveness is caused by our knowledge that things quickly freeze in space.
Freezing is produced by a combination of temperature and pressure, but because the former fluctuates a lot more than the latter in our daily experience, the role of pressure isn’t part of our intuition. But in a vacuum, things freeze even at relatively high temperatures.
Yep, in space, getting rid of excess heat is a much harder problem than you’d think, because radiation is a lot less efficient compared to convection (distribution of heat through movement of fluid like air or water).
As an earthling, you have evolved over the course of billions of years to deal with sunlight at a distance of one astronomical unit. That’s the distance of the earth’s orbit. That’s probably the most comfortable distance.
The Apollo moon missions used a so-called “barbecue” mode that rotated the capsules at three revolutions per hour. They did this during the 3-4 day coast phases to and from the moon. As far as I know this was able to mostly hold the interior temperatures in the “survivable” range.
That’s a good starting point, but caveats:
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My bet is that most of our thermal circulation is via the movement of our blood. That’s probably not directly analogous to spacecraft.
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If one isn’t just talking thermal, we do burn at 1AU. Go lie in the sun without cover long enough – especially if you’re pale-skinned – long enough, and you’ll get burned. Without the atmosphere, we’d be hit by more UV light, too.
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Where you are but up.
Seems like a good question for Randall Monroe, if he hasn’t already done something similar.
That or TheStraightDope!
You should post this in c/askScience
Even once you achieve the perfect rotation, the unfiltered UV would likely eventually give you cancer.
