Is all of our universe… lit? Can you be hurtling through space and accidentally fly head first into a planet because oops you didn’t have your headlights on?
In: Physics
>Space … is big. Really big. You just won’t believe how vastly hugely mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.
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>- Douglas Adams, “The Hitchhiker’s Guide to the Galaxy”
The chances of something running into something else in space (other than the occasional hydrogen atom) is miniscule.
That said, most of interstellar space is also quite dark. In deep space, nothing’s going to be illuminated like you’d see on Earth. If anything, something large or very close by would only be visible as a silhouette against a the background star field of space (and, unless you’re inside a galaxy, that star field is going to be very very very dim.
For something the size of a planet, you might notice the gravitational pull of the planet long before you otherwise sense it (if you think to look for it). If not that, everything emits a tiny amount of radiation, so there’s a very dim and invisible-to-the-naked-eye glow to everything, if you have the instrumentation to see it.
If the object was, say, the size of a box truck, floating in deep space, you’d probably bump into it before you noticed it without with some sort of active scanning technology.
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