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Originally Posted by polak
Light dispurses as it travels away from the source. Only a small fraction of the light from the sun hits this planet (which is further than pluto, at least in the time we've been looking with telescopes) and then even less of that light hits earth on it's way back.
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Yeah, the way it makes the most sense to me is to think of a planet's orbit as a sphere that sunlight is spread over. No matter how far out you go, the amount of sunlight is the same, but the size of the sphere increases tremendously:
On earth, the sunlight we get is spread over a sphere of .28 billion km2.
On Neptune, the same amount of sunlight is spread over 254 billion km2.
At the sort of distance this planet is, you're talking about this same amount of light spread over 11159 billion km2. Or, if my math is right, light there is 39855 times dimmer than on earth.
And that is only at its closest point.