Universe Sandbox ² is a physics based space simulator.
Create, destroy, and interact on a scale you've never before imagined. Shoot asteroids at the Earth or cause a run away greenhouse effect. Rip apart the rings of Saturn or blow up the Sun. Watch sea ice grow and recede with the seasons because of the tilt of the Earth: change the tilt and change the seasons. Or move the Earth further from the Sun and freeze the entire planet.