Over the course of a human lifetime, do any of the photons emitted by humans via blackbody radiation ever successfully make it through the atmosphere and into space?

Submitted by hippofountain t3_11sfwc1 in askscience

My understanding is that humans emit countless infrared photons during their lifetime. I also know that they are frequently absorbed by other matter. I am wondering if even one photon can be expected to make it through the atmosphere in, say, an 80 year lifespan.

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viscence t1_jchzsoa wrote

At body temperature, you emit around one or two times ten to the power of 22 photons per sterradian per second per meter squared, at around several to tens of microns of wavelength. The atmosphere doesn't let all of these through, but a lot! if you have a surface area of 1 square meter and lived 80 years under an open cloudless sky of 2*pi sterradians, you've probably sent more than 100000000000000000000000000000000 photons into space.

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hippofountain OP t1_jcj5zku wrote

Thank you so much! You have no idea how long I've wondered this.

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rootofallworlds t1_jcmg0qt wrote

Even if you completely covered every other part of the body, if you look at the sky, about 20% of the thermal radiation from your eyeballs escapes into space.

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hippofountain OP t1_jcnla5y wrote

This is absolutely wild. I figured that some photons must make it through, but these numbers are stunning. Thanks for the extra info!

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