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I always wonder what would happen if you put a fully enclosed glass terrarium in space. How would it fair. Not big either. Grape fruit sized.
by hparadiz 1y ago
I always wonder what would happen if you put a fully enclosed glass terrarium in space. How would it fair. Not big either. Grape fruit sized.
- Mistletoe 1y agoIf it was in the sun it would be incinerated and in the shade it would freeze right?
- nine_k 1y agoThe other side would radiate, losing the heat. Earth, being in a similar position, is neither incinerated nor refrigerated, though different sides of it can be hot or cold.
- 0_____0 1y agoEarth has the benefit of a thermal mass that's at least a couple times larger than your average terrarium.
- nitwit005 1y agoEverything exposed to the sun will heat up until the energy it emits balances out the incoming energy. Being a larger mass just means an object will take longer to heat up.
- cma 1y agoDepending on how rich in internal radioactive sources of heat it isn't scale free with mass. Larger masses of the same makeup will reach different thermal equilibrium since the surface area grows at a slower rate than the internal heat production from decay which scales with mass. I don't know if it is significant, but tidal sources of heat might not scale the same either.
- nitwit005 1y agoI think we can safely say the planet made of uranium is an edge case. The Earth's internal radioactivity is a miniscule energy source compared to the sun.
- cma 1y agoYes it's small, but: At least during emergence of life there was the faint young sun + higher proportions of radioactive elements, so could have made up 0.2% of outgoing thermal radiation or so on earth (ignoring outflow of residual heat from early collisions). I think 5-10 earth masses is the limit for terrestrial planets, and you can imagine having say 10x more radioactive elements and still hospitable to life, rather than being made of solid uranium. So maybe double digit percentage radiant heat outflow differences between very small and very large on those.
- mr_toad 1y agoPresumably a spherical ball of air would be able to transfer heat more quickly (from the hot to the cold side) than the same volume spread out as a very thin hollow layer.
- nine_k 1y agoSphere's surface grows as radius squared, but volume grows as radius cubed. Hence a small terrarium will quickly freeze, and a huge terrarium will eventually fry. There is an optimal size for a terrarium, given its orbit, that keeps its internal temperature within the habitable range. Also it would need many more plants than animals. I would rather go with an aquarium.
- tbrownaw 1y agoWhat does volume have to do with energy balance?
- thfuran 1y agoHeat is transferred through the surface area and produced by the volume (assuming there's something going on in the system that's exothermic).
- jjk166 1y agoHeat isn't produced by the volume. Heat may be produced by something within the volume, but it's not the volume's existence that causes heat to be produced. There is no fundamental reason a bigger terrarium should produce more heat, nonetheless that heat production should be directly proportional to volume.
- thfuran 1y agoYes, obviously it'd be the stuff in the terrarium rather than the space it occupies that produces heat, but the amount of stuff you can fit in it is determined by the occupiable space. And if that stuff is producing heat, such as by decay, there's going to be more heat with more stuff. Though even if it cooks itself for a while, it should eventually settle on a temperature determined mostly by orbital parameters and material properties rather than size, since the stuff can't be net exothermic forever. But greater atmospheric depth probably still increases equilibrium temperature by reducing heat transfer through that side of the terrarium.
- ilamont 1y agoGiant terrariums in space was the premise of one of the great science fiction films of the early 1970s: Silent Running https://cult-scifi.com/silent-running-1972-movie/ https://cult-scifi.com/silent-running-1972-movie/
- wowczarek 1y agoI am me and I approve this message. The habitats, the people, the robots, and a beautiful theme song by the great Joan Baez. Silent Running is a great film indeed.