SpaceEngine

a free space simulation program that lets you explore the universe in three dimensions, from planet Earth to the most distant galaxies.

Stellarium

Imagine having access to the software used by planetariums? Enter open-source Stellarium, which has a catalog of 600,000 stars. You can get access to more catalogs and discover up to 210 million stars. Zoom in on the twinkling stars all you want.

Eolisa

EOLi (Earth Observation Link) is the European Space Agency's client for Earth Observation Catalogue and Ordering Services.

Planet Defender

3D turret space shooter. 16 missions, Dozens of Enemies, Incredible gameplay. Simple controls. Reflecting field usage – let enemies destroy themselves.