None of the planets emit significant visible light, so the side facing away from the sun is dark. Some do emit infra-red or even x-ray energy that can be imaged.
This image was taken by the Juno spacecraft
Off-topic a bit but has any NASA probe sent dark-side pictures of planets and are they dark?
None of the planets emit significant visible light, so the side facing away from the sun is dark. Some do emit infra-red or even x-ray energy that can be imaged.
This image was taken by the Juno spacecraft
There are no dark sides to the planets; none of them are tidally locked. I think Jupiter rotates on its axis once every ten hours or so, so a probe can almost watch it turn in real time.