Something that's been bugging me for a few years now, but I haven't been able to find information anywhere...

How bright is the 'daytime' in the outer solar system? On Pluto, for example, I imagine that even their daytime will be pretty much total darkness, but how about Jupiter, Saturn, Uranus, Neptune and their respective moons? Is the sunlight that reaches them sufficient for any kind of illumination or what? In pictures we have of Jupiter and Saturn for example, their colors and surfaces look really bright, so I'm thinking there can't be total darkness there, or?

Any thoughts would be appreciated.

The luminosity of the Sun is about 4x10^26W. So at the Earth's upper atmosphere we receive a flux of 1422 W m-2. At the surface of the upper atmosphere of Jupiter they receive only 3.7% of what the Earth receives. On Pluto this drops to about 0.06% of what is incident on the Earth. So clearly Pluto is a very dim place.
Other factors must be considered though. There is no real surface it seems on Jupiter. The atmosphere is over 1000 km deep and very opaque, consisting of mostly hydrogen and helium. On a liquid surface at 1000km very few photons will be able to reach down and illuminate other objects. So it will be very dark also.

An excellent point, I hadn't considered the luminosity absorption by the atmo/hydrosphere.

Even still, can anybody figure out a rough idea of how dark it would be on, say, a moon or asteroid around Jupiter? Is it darker than a cloudy rural midnight on Earth? Would the human eye be able to see anything?

I suppose even on Pluto, starlight gives some kind of illumination. So would it be correct to assume that nowhere in the solar system can it get darker than a rural (no artificial lighting) starlit night? Earth starlit nights away from light sources are about as dark as it could get, even in the outer solar system?

(Excluding obviously underground/indoors/in shadow environments.)

For some reason, this topic fascinates me -- exactly *how* dark would it be in more distant orbits. If anybody has any visual aids to help picture it, I'd love to hear any.

stevewin's answer is definately key to understanding what is going on.

but I think there are some other questions to be answered first:

on earth, are you taking into consideration a new moon? is the moon visible?

Also, consider this: just as very few photons are able to reach through jupiters thick atmosphere which limits light as stevewin stated; there is also the reflectiveness of the ground surface which plays into account on how "dark" something seems.

hypothetically, if pluto absorbed most of the 0.03% of light (normalized to a sunny day per stevewin), i imagine standing on the surface of pluto, you would honestly see equivalently black (ground) and black /w stars and sun. the ground, to the eyes, might be perceived as an empty void of space where no stars are appearant. naturally, the normal force would give your feet or bum (if sitting) the sensation of a solid object, but I don't think you'ld see it.

however, as pluto is speculated to be largely ice and gas, and we know ice is semi-reflective, the surface of pluto would probably appear to have a ice like reflection/refraction in the general direction of the brightest sources--namely the sun. so perhaps pluto would be perceived with the same brightness as if it were made of light-absorbing compounds, but perhaps with reflective glistens. then again, it may appear to be as unnoticeable as black ice (ice at night that you can't see on the road)

all in all, I'd say this much--it probably won't be as dark as mentioned in either of the above two examples since pluto can be observed in the visible light spectrum w/ a powerful enough telescope--it isn't "black"

True, in the best observations we have Pluto appears to be highly reflective. In fact it's albedo is 0.49-0.65 which makes it one of the brightest planets. This is probably due to methane and nitrogen ice on the surface.
How bright would it be for a person standing on the surface and gazing out across the landscape? I don't know. I guess it would still be pretty dark, illuminated mainly by the other stars, even with the highly reflective surface.
The Sun at this distance must be really small and subtend a very small angle. It would definitely be the brightest star, but I'm not exactly sure how big it would seem.

Yeah, I'm thinking that if we can actually *see* planets in the visible light spectrum with our own eyes from all the way on Earth, then certainly we should be able to see their surface from much closer by, right? It would seem to make sense to me.

doesnt really answer your question but cool to think about.
on pluto the sun isnt the brightest star in the sky.