You’ve probably heard the Doppler effect – think of the change in pitch of an ambulance or horn as it passes by. This occurs when the frequency of a wave stretches or compresses as it moves relative to its source. It’s also a phenomenon that has helped astronomers like graduate student Lauren Weiss of the University of California, Berkeley to find planets around distant stars.

"So, this is true with light, as well as sound. So we are measuring the change in pitch of the light, as the star moves in space. And the reason that light changes its pitch, or frequency, is that there’s a planet orbiting the star and making the star wobble back and forth."

Weiss says that the Doppler technique is not new in astronomy, but her team has recently made new discoveries with the help of one using the Automated Planet Finder, which is a robotic telescope.

"It is one of the first times a robot has used the Doppler method to find planets around other stars."