Just how fantastical a planet can be and still support recognizable life isn’t just a question for science fiction. Astronomers are searching the stars for otherworldly inhabitants, and they need a road map. Which planets are most likely to harbor life? That’s where geoscientists’ imaginations come in. Applying their knowledge of how our world works and what allows life to flourish, they are envisioning what kind of other planetary configurations could sustain thriving biospheres.

You don’t necessarily need an Earth-like planet to support Earth-like life, new research suggests. For decades, thinking about the best way to search for extraterrestrials has centered on a “Goldilocks” zone where temperatures are “just right” for liquid water, a key ingredient for life, to wet the surface of an Earth doppelgänger. But now it’s time to think outside the Goldilocks zone, some scientists say. Unearthly mechanisms could keep greenhouse gas levels in check and warm planets in the coldest outer reaches of a solar system. Life itself could even play a starring role in a planet’s enduring habitability.

“It’s an exciting time,” says Harvard planetary scientist Robin Wordsworth. “There’s still a ton for us to learn about the way different planets behave. The Goldilocks zone is just a very rough guide, and we need to keep an open mind.”

To read more, click here.