Do-it-yourself solar system

If you’ve always wanted to build your own solar system, roll up your sleeves — it’s time to see what you’ve got. SuperPlanetCrash is an online solar system simulator, set up as a game. The goal is to plop planets around a star and keep them orbiting for 500 years. Seems simple enough, but gravity is a formidable opponent. Each planet or star adds to the gravitational tug-of-war with every other body. Get the balance wrong, and planets crash together or are flung into interstellar space.

The game, created by astronomer Stefano Meschiari of the University of Texas at Austin, simulates the movements of planets and stars using the same computer code that researchers use to find exoplanets. Points are awarded for how numerous, how massive and how crowded players make their planetary fiefdoms. Earn bonus points for keeping things stable in the central star’s habitable zone, the temperate region suitable for liquid water.

Coming up with bizarre arrangements can be a lot of fun. Wonder how long an ice giant would last between two dwarf stars? Or if 11 super-Earths can squeeze into one habitable zone? For an extra challenge, see if you can get a planet to go counterclockwise. Win or lose, SuperPlanetCrash is the planetary sandbox you’ve been waiting for.