Size matters. Especially when it comes to starships, giant monsters, buildings, and . . . well, pretty much anything else that you can obsessively categorize using common measurement systems. Here are ...

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 ...

Scientists using NASA’s Kepler, a space telescope, recently discovered six planets made of a mix of rock and gases orbiting a single sun-like star, known as Kepler-11, which is located approximately 2 ...