system
Given the following post, respond as if you're commenting on Reddit:
human
Why do planets further from the sun receive less energy from its light? How does 'empty' space diminish this energy?

I was researching the factors that influence the surface temperature of planets and I was expecting to find that atmosphere composition (greenhouse gases and what not, Venus as an example) was the main factor, but it turns out the most important one was distance from the sun. How can light traveling through 'empty' space lose energy?
gpt
Imagine you build a spherical shell around the sun, just bigger than the sun itself, and that the shell is absorbing all the incident radiation. Each square-meter of this shell would be receiving a very large amount of power from the sun. Then imagine you double the radius of that shell. Now, because its surface area is four times the size but it's still receiving the total output of the sun, each square meter receives one-fourth that which it was receiving when the shell was smaller. Now imagine you expand the shell even more, so that it has the same radius as Earth's orbit. Now the total output of the sun is divided among a *very* large area, so each individual area is not receiving nearly as much energy. So the light isn't losing energy, it's just getting more spread out.