First reported in 1912 by Austrian physicist Victor Hess, cosmic rays were discovered after a series of balloon ascents meant to explore ionizing radiation that was first detected on an electroscope.

Cosmic rays are particles from outer space that travel across ... Then in 1912, Austrian physicist Victor Hess flew a balloon to an altitude of more than 17,000 feet and found that the radiation rate ...

DURING the last ascent of the balloon F.NM.S. (August 18, 1934), we had the opportunity of measuring with precision the intensity of cosmic rays at altitudes of about 12,000 m., 15,000 m.