Radio astronomers study what’s going on in outer space by using radio waves (as opposed to telescopes, which use light in the visible region of the spectrum). This approach has some distinct advantages, perhaps the most obvious being that radio astronomers can work at any time of the day while astronomers who rely on light telescopes can only work at night. Radio astronomy relies on monitoring weak radio wave signals coming in from outer space, and knowing how to interpret these signals, to draw conclusions about the locations of celestial bodies and events that have taken place far, far away.