Life is a fragile thing — slight variations in a planet’s mass or its distance from its sun can all mean the difference between a thriving global ecosystem and a cold, dead rock floating through space. If I sound bitter, it’s because I’ve just created five or six uninhabitable worlds in Extreme Planet Makeover, a planet-building simulator from NASA and the California Institute of Technology’s Jet Propulsion Laboratory.

This fun application lets you manipulate several conditions that make a planet conducive to life as we know it — the planet’s age, its distance from the sun, the planet it’s based on (more on that in a minute), what type of star it orbits, and more. To create a habitable planet, you have to hit a very narrow nexus of each of the factors, and your students can plan to spend a good deal of trial and error trying to build something they could live on.

You can choose between three planets to use as a template — Earth, Mars, and Gliese 581 d, a large “Super-Earth” with a rocky surface that scientists think could possibly harbor life. I think it’s pretty fun to play around with a distant planet that might actually have life on it, just as it is to renovate Mars into a place where some little green men might want to settle down.

Through playing this game, I learned several new things about the planetary life cycle, like the fact that as a planet gets older, its core cools down and all liquid water sinks into the crust, which is only a problem if you’re an organism that needs water to live. Extreme Planet Makeover has lots of facts like that, there for the learning.

Of course, this game really brings to light how little we know about life in the universe. Is an Earth-like planet the only place life could survive? We just don’t know, but Extreme Planet Makeover does a good job of illustrating what we do know. And with enough patience and mouse clicking, you too can finally build a planet you could theoretically call home (see Planet Ferris above).

Extreme Planet Makeover

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Another fabulous site from NASA: Solar Sytem Exploration

See the planets in motion with the Solar System Visualizer

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