Thousands of candidate exoplanets have emerged in the decades since astronomers first found worlds around other stars. Only a few of those are planets humans might recognize as resembling our Earth. NASA’s Kepler spacecraft found many of these.
Astronomers now want to find Earth-like planets orbiting in the habitable zones of their stars — the region where liquid surface water can exist. Then, their instruments will sniff out atmospheric compositions searching for gases that shouldn’t be there, like oxygen. Such a find might provide the first evidence of life on another world. Learn more about this search with Liz Kruesi’s “The next search for Earth-like worlds.”