physics

[mick@ret]

what causes us to see the moons of jupiter

[heathfield]

The same thing that 'causes' us to see our own moon, though in the case of Jupiter's moons, you might need binoculars or a telescope.

[Loosehead]

reflected sunlight

[demitry-hed]

the reflected rays of the sun

[sm:ash]

basically what they said.... though what we see is in the past.. based on distance and speed of light :)