I’ve read a 3 month old thread that explains how the light of the sun transfer heat but i was wondering why do the light of other stars don’t seem to affect us.
In: Physics
Because they’re many lightyears away and the energy is too spread out by the time it reaches us.
Our sun is 8 minutes away, if you travel as fast as light does.
The next nearest star is almost 4 years away if you travel as fast as light does.
Just doing a naive calculation here.. the heat we get from that star is probably somewhere around 262,800x less than the heat we we get from our sun.
(4 x 365 x 24 x 60 / 8 = 262,800)
Edit: factor of 8
Whenever you increase your distance from a light source by a certain degree, you reduce the amount of light you get by the square of that degree. So if you moved three times further away from the light source, it appears to be 1/9 as bright.
Other stars are millions of times further away from us at the closest, so if they were exactly as bright as the sun they would appear about 1 quadrillionth as bright. And likewise, that means about a quadrillionth much as heat from them gets to us.
Because of the inverse square law. A sphere’s surface area grows by the square of its radius. That means if you go twice as far out from a star, its radiation flux is only 1/4th of what it was before. This adds up fast. The radiation flux from even “nearby” stars is so tiny we can barely see them at all.
Because they are so far away, only an *incredibly small* portion of their energy reaches us. The rest has gone off in other directions.
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