During its 4.5-billion-year life span, Earth’s been hit by countless asteroids. (Despite Jupiter’s noble attempts at defending it.) But while it’s easy to imagine the damage they’ve done, just how big ...

We have detected only one transiting planet that has a mass below 10 Earth masses. This world, CoRoT-7b (named after the European Convection, Rotation and planetary Transits satellite) has a radius ...

Astronomers studying extreme planetary systems have identified worlds so massive that they rival the smallest stars in size. These giant planets blur the line between planetary and stellar ...