The new discovery of seven alien Earth-like planets in a faraway solar system is a major milestone in our hunt for extraterrestrial life, and experts investigate the secrets of TRAPPIST-1's mysterious worlds to reveal if we're truly alone in the universe.

New discoveries are helping experts in their search for the first alien moon outside our solar system, which could be Earth-like worlds with the potential for life. So far, they haven't found any, but twenty-first-century methods might change everything.