Space Engine is a program that allows you to explore the cosmos at your leisure, from faraway galaxies to nearby...

Space Engine is a program that allows you to explore the cosmos at your leisure, from faraway galaxies to nearby worlds.

Is free to download and play.

Recreates a cubic 10x10x10 gigaparsec area of the known universe that’s open to exploration from corner to corner.

Contains a large catalogue of actual astronomical objects, including galaxies, stars, planets, dwarf planets, moons, asteroids, comets, and black holes, with more intended to be added in the future.

Procedurally generates galaxies, stars, planets, moons, and other objects not known to us according to reasonable probabilities. When exploring, you never quite know what you’re going to find.

Includes 10,000 catalogued galaxies, possibly billions more procedural galaxies, many trillions of stars, and even more planets and moons to explore. You can spend your entire lifetime looking at every single star system and never even make it to the next galaxy.

Gives you the ability to travel through space at any speed from 1 meter per second to 1 gigaparsec per second, allowing you to swing across superclusters, leap through galaxies, warp between stars, hop between planets, and glide over moons.

Presents the cosmos with stunning graphics and detail, from the gravitational lensing of black holes and neutron stars to the shadows of rings across planetary atmospheres.

PS: Space Engine is also a work in progress and is still in the process of being updated. It also requires a powerful PC to run well.
Give it a try:
http://en.spaceengine.org/