Sometimes it's nice to step into science-fiction territory. Writer and artist Ron Miller wanted to see what it would look like if the Earth's moon was replaced by other planets from our solar system. He created a series of images to show what it would look like from our perspective, keeping the various planets at the same distance as the moon is from us (about 240,000 miles). Above is his rendition of a Jupiter moon, and below is Mars.
But it's interesting to imagine what the night sky might look like if one of the Solar System's planets were to replace our moon. (We'd have to ignore things like tides and gravitation, but that's the advantage of doing things in the mind's eye.) So what would we see if we were to replace the moon with Mars? The red planet is almost exactly twice the size of the Moon, so it would appear twice as big in the Earth's sky. It would be easy to see with the naked eye details on the surface of the planet that were previously visible only through telescopes. You could watch the ice caps grow and shrink during the changing seasons, see dust storms form and move across the planet and make out features like Vallis Marineris and Olympus Mons. [...]
Forty times larger than the Moon, Jupiter would stretch 20 degrees across the sky. It would also look a little different from the telescopic and spacecraft photos we're used to seeing. This close, we'd be looking "up" at the northern hemisphere and "down" at the southern hemisphere, so the cloud bands would be distinctly curved in perspective. In fact, we'd not be able to see the north and south poles of the planet.
For the whole series of images and Ron's complete commentary, check out his post at io9.
You can also check out his personal Kinja website: Ron Miller
I'll leave you with beautiful Saturn: