Celestia is a 3D simulator of the Solar System. It’s pretty amazing actually. You can move about, lock onto planets, land on their surface. It’s not exactly limited to the solar system, more like the Universe, i.e. as much of it is known to mankind. You can even move out and visit other galaxies, systems, e.t.c.
It also has a “TLC Feature 😀 ” that enables you to speed up or slow down time, or even stop it, or reverse it. That;s not all, it has a lot of features and is definitely worth trying.
Installing it in Ubuntu is relatively easy, simply fire up a terminal(CTRL + Alt + T), and paste the following code:
sudo apt-get install celestia-gnome