(Westend61/Getty Images) Humans have been tattooing themselves for thousands of years, for spiritual, cultural, or personal reasons. Long before we were covering ourselves in ironic stick'n'pokes, ...

An artist's impression of an exoplanet transiting a main-sequence star. (ESA/Hubble/NASA/M. Kornmesser) Of all the strange worlds in our Milky Way galaxy, some of the most mysterious are those hanging ...