Just signing in to advise of a free prog called Celestia which is technically & graphically amazing. Anyone with an interest in the planets should give it a go - it is of comercial quality and is keeping me glued.
There are lots of hi res textures to add to it and it would be a great teaching aid as you can follow the seasons.
It is all kept going by enthusiasts - give it a look! Download the hi res Jupiter skins - fantastic