Space Engine is a free OpenGL based program witch allow you to explore the universe in 3D, in a Celestia style. With it you can choose to see the known world or you can go inside various real or generated galaxies to see procedural stars, planets and moons. Space Engine can generate from galaxies to lands. It has a newton-based (but reallyyy simple) physics engine allowing you to travel like a ship. The 0.96 update adds real spacecraft (by "real" I mean that you can see them, not that they are or were really launched). So, this is a picture from Space Engine:
(you can see what type of "spacecraft" are in this game, and how procedural planets renders)
A new feature came with 0.96 is black hole gravitational lensing, like that:
Space Engine can renders eclipses:
Generated galaxy viewed from the side:
And Milky Way seen from inside the LMC (orbiting a procedural planet) :
And a screen showing the capacity of SpaceEngine to generate terrains:
Quickly, I've started to find some nice planets, and one day ... I found "Temperate Terra with Life" !
This one is a cool oceania, with only land on the night side of the planet:
Returning to the known world, space sunset from the Earth:
Here is the official Space Engine site:
http://en.spaceengine.org/
If you want even more pictures, come here:
http://en.spaceengine.org/forum/10-432-1
And I'll leave you with a skybox picture and some videos (not made by me) :
Space Engine 0.96 Update - kurtijmac
The Size of the Known Universe - JSSJR90
Billions and billions - pebblegarden
Probe-style video - bboyenw