The idea of planets orbiting other stars, possibly harboring life, is hardly a new one; visionaries and science fiction writers have let their imaginations run in this direction for decades, even centuries. It is only since the 1990s, however, that technology has advanced to the point to allow fruitful searches for extrasolar planets to be carried out. Because stars are immensely bright compared to any planets that might be circling them, however, direct observation of extrasolar planets is akin to observing a firefly hovering next to a stadium light. Indirect means of detection must be used, and one common method is to observe variations in a star's radial velocity.

Radial velocity is the velocity of an object along the observer's line of sight. As a planet orbits its parent star, it tugs the star back and forth slightly, so instead of moving in a uniform orbit...