system
Given the following post, respond as if you're commenting on Reddit:
human
[general] If a vampire is in space, how far from the sun do they have to be to be safe?

So, if a vampire was in space in earth orbit, or on the moon, when the sun came up they'd be screwed. But starlight is fine, as is the reflected sunlight from the moon, so there has to be a limit. Would they be OK on mars? How about further out? A planetary atmosphere filters out a certain amount of radiation and protects us, does it also filter out whatever harms vampires?
gpt
The moon is very small in the sky and is pretty dark, so it reflects very little light. The bigger issue is that they're generally okay with sunlight reflected from walls and such.

The amount of sunlight they get is inversely proportional to the square of the distance from the sun. I'd say ten times darker is probably enough, which would mean they'd have to be about 3 AU away from the sun. That would be at around the outer edge of the asteroid belt.

That's assuming they don't need to breathe, but as undead, they probably don't.