Exoplanets like Earth have been discovered but not all Earth-like planets are equal when it comes to alien life.

Earth, sun, moon: three objects in space whose interactions have a pretty big impact on our lives. Earth orbits the sun once a year, and it rotates on its axis about once a day (depending on your ...

Illustrations of the Huttonian theory of the earth a facsimile reprint with an introd. by George W. White ...