Big Ear, a radio telescope at Ohio State University received a strong, apparently extraterrestrial radio signal that became known as the Wow! signal.

The Ohio State University Radio Observatory was a Kraus-type radio telescope located on the grounds of the Perkins Observatory at Ohio Wesleyan University in Delaware, Ohio from 1963 to 1998. Known as Big Ear, the observatory was part of Ohio State University's Search for Extraterrestrial Intelligence (SETI) project. The telescope was designed by John D. Kraus. Construction of the Big Ear began in 1956 and was completed in 1961, and it was finally turned on for the first time in 1963.

A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum, just as optical telescopes are used to make observations in the visible portion of the spectrum in traditional optical astronomy. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night.

The Ohio State University is a public land-grant research university in Columbus, Ohio, United States. A member of the University System of Ohio, it was founded in 1870. It is one of the largest universities by enrollment in the United States, with nearly 50,000 undergraduate students and nearly 15,000 graduate students. The university consists of sixteen colleges and offers over 400 degree programs at the undergraduate and graduate levels.

Radio waves are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths greater than 1 millimeter, about the diameter of a grain of rice. Radio waves with frequencies above about 1 GHz and wavelengths shorter than 30 centimeters are called microwaves. Like all electromagnetic waves, radio waves in vacuum travel at the speed of light, and in the Earth's atmosphere at a slightly lower speed. Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects.