In August 1924, the US government declared a "National Radio Silence Day" to detect extraterrestrial signals. Civilians were asked to keep radio silence for five minutes on the hour, every hour, for 36 hours. The US Naval Observatory lifted a radio receiver three kilometers off the ground to detect Martian signals; they even had a cryptographer on hand to translate messages. Unfortunately, there was only silence, but as technology improves, so do our chances of finding life out there.
Scanning the airwaves for messages could put us in contact with other intelligent life, but what is the likelihood that any life is out there? New research led by astronomy PhD student Erik Petigura suggests it's more likely than previously thought. Petigura used NASA's Kepler telescope to look for Earth-like planets. Kepler, an observatory launched into space in 2009, was designed to survey the Milky Way for exoplanets. Without interference from the Earth's gravitational pull, ambient light, and the various celestial figures that can get in the way of measurements (like the Sun and the Moon), Kepler has a much better view of the cosmos than any Earth-bound telescope.