Life once existed on Mars, but a series of devastating mass extinctions have made present-day life nearly impossible. The latest science shows how Martian life keeps bouncing back as it transforms from a watery world like Earth into a desert planet.

Discoveries of new planets have revealed countless worlds much stranger than Earth. Some of these strange worlds don't have stars, others are made out of diamonds. Will we ever find a planet like Earth, or are these distant worlds stranger than fiction?