NAUTILUS - Hold a grain of sand up to the night sky at arm’s length. There are thousands of galaxies in that miniscule fraction of the heavens. Galaxies like ours hold hundreds of billions of stars—a good portion of which host planets. And a number of these are in the “habitable zone,” that just-right distance from a star where the temperature might fall between zero and 100 degrees Celsius, the right conditions for liquid water. Perhaps for life, too.
But the habitable zone is often misunderstood. A planet within the habitable zone may not host water, or be even remotely habitable. There are countless other factors at play—some of them buried deep below the surface. “The habitable zone is a useful concept for astronomers,” says Noah Tuchow, an astronomer at NASA’s Goddard Space Flight Center who studies the effect of the habitable zone on planets. “It’s best thought of as a hypothesis.”
A hard lesson in these odds sits just next door to us, in our solar system.
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These types of nuanced dynamics, “really opened the doorway in thinking more broadly about the many, many differences between Venus and Earth than just the amount of energy received from the sun,” says Stephen Kane, a planetary astrophysicist at the University of California, Riverside and one of the coauthors of the recent paper praising the usefulness of Venus’ barrenness.