I have a question about what would happen to a household lightbulb burning in space. Since space is a near vacuum, a lightbulb can’t shed energy with convection or conduction. It can only emit energy by radiation. My theory is that a burning lightbulb would rapidly overheat and melt. Another person believes a lightbulb would burn just fine. Anyone got the answer?
well… i really completely forget about normal household bulbs, but halogen bulbs are pressurized… so i would guess with zero pressure they would likely explode in space… no burning there 
also wouldnt you have to figure the fact one side of the bulb would be very hot and the ‘dark side of the bulb’ would be very cold… it might not even survive just floating there, much less with 60-150 watts running through it…
something, the metal in the bulb’s base would conduct heat pretty evenly throughout itself and the portion of the glass that it touches, and the glass itself is transparent to visible and IR radiation. I don’t think heat differentials will be a huge problem here.
Standard incandescent bulbs are not full of much by way of gases. Some argon, maybe, but at a low pressure. I don’t know if the pressure would be high enough to rupture the glass, but it wouldn’t matter if it was: Incandescent bulbs work best in a vacuum anyway. So even without the glass and the gas, you’d still have heat and light.
The final problem relates to the temperature extremes: With space a frigid 3K in the dark and ultra-hot near stars, you might get metal fatigue problems. I know tin, for example, will degrade badly in the cold. Incandescent filaments are tungsten, however, and I don’t know how that would hold up.
SuzyQ,
that is a really fascinating question, I love this kind of mind-bogglers.
I am pretty sure you are right, generally.
Often you see warning signs in lamps not to use a stronger bulb than whatever.
Obviously there is the danger of overheating.
The radiation will be heating the surrounding lamp to higher and higher temperatures with time, even when using a very low power bulb. But in our gravitational dynamic atmosphere the convection transports away the heat pretty fast, faster than a low power bulb can build up the heat.
No atmosphere or no gravitation (that just crossed my mind, you really have to consider a lot of things when building a space station) and the lamp overheats.
However, you seem to be thinking of an isolated bulb, indicating there is no surrounding that could be ignited.
Would every light bulb quickly burn out? I doubt so, probably only high power ones will do.
There are dopers that could most likely calculate the energy dissipation by radiation depending on surface area and the watts of the bulb.
My guess is, the borderline will even be a little below 50 watts, most standard household bulbs will burn out.
something clever,
the glass walls of halogen lamps hold in so much pressure and are over-designed for safety that the missing 1 at on the outside will not cause an explosion.
There are tiny halogen lamps where the bulbs are behind another safety glass which restricts air circulation. This lamps usually carry stickers not to touch them because of the heat, rightfully.
This type halogen bulb should tolerate the space environment.
The other type, that requires cooling fans, as in a slide projector, are clearly not designed for interstellar use.
MummyCave
Are you sure about that; I thought that the gas inside the envelope was there to give evaporated metal atoms a chance of ‘bouncing’ back onto the filament.
That’s how a halogen lamp works. Normal bulbs usually contain argon which doesn’t have that feature, if I understand that cite correctly.
I think light bulbs would work well in space if you break and remove the glass. A filament should glow just fine in high-grade vacuum. And a light bulb with an extra-thick glass would work just fine. Whether commercial lightbulbs would work in space, I’m not very sure. It might, but I wouldn’t count on it.