The Planet Factory: Exoplanets and the Search for a Second Earth

Twenty years ago, the search for planets outside the Solar System was a job restricted to science-fiction writers. Now it's one of the fastest-growing fields in astronomy with thousands of exoplanets discovered to date, and the number is rising fast.

These new-found worlds are more alien than anything in fiction. Planets larger than Jupiter with years lasting a week; others with two suns lighting their skies, or with no sun at all. Planets with diamond mantles supporting oceans of tar; possi...