Big Ear

flat reflector

The Big Ear flat reflector.

parabolic reflector

The parabolic reflector.

Big Ear was the radio telescope of Ohio State University Radio Observatory which was used in the Ohio SETI Program, the longest-running project of its kind carried out to date. It will best be remembered for its detection of the so-called Wow! signal.


The brainchild of Observatory Director and founder John Kraus, Big Ear was larger than three football fields and of an unusual design that has subsequently been copied at other sites around the world. It consisted of a flat, tiltable reflector 104 meters (340 feet) long by 30 meters (100 feet) high, a fixed standing parabolic reflector 110 meters (360 feet) long by 21 meters (70 feet) high, an aluminum-covered ground plane 110 meters (360 feet) wide by 152 meters (500 feet) long, and two feed horns mounted on a movable assembly. Its sensitivity was equivalent to that of a single circular dish-type radio telescope 53 meters (175 feet) in diameter. Big Ear surveyed the sky by drift-scan. The flat tiltable reflector was pointed skyward to pick up cosmic radio waves which were then bounced over to the parabolic reflector to be focused into a beam. This beam was reflected back across the ground plane to the feed horns. The aluminum layer of the ground plane kept the feeble signals from being absorbed by the ground. After a few days of observing in one position, the tiltable reflector was moved slightly to allow a different section of the sky to be scanned.


In 1998, Big Ear was demolished to make way for a golf course. One hundred small pieces of the metal mesh covering the instrument were rescued by members of the SETI League and offered in exchange for a minimum $100 donation with proceeds divided between the SETI League and the Ohio State University Radio Observatory. The latter is now engaged in construction of the Argus radio telescope.