Very nice--you might want to check some spelling and grammar mistakes in the Saturn's Rings section...
and as a side note: the font you use for the words "facts and figures" would be more appropriate, in my oppinion, to use for all the text--it would give the text a feeling of being some scientists notes.
very nice, I wish I had the patience to go through and look at all of the planets stuff you have up.
Ironically, the only thing I'd change in this one are the rings. When I look at them, I feel like I have double vision. They seem more prominent on all the photos I look at. And the planet itself is more striped with clouds in photos. Those are the big things I'd suggest changes for in this piece. I hope you don't mind constructive criticism.