A physicist rode hot air balloons to 5,300 metres and found radiation raining from space

In 1912, Victor Hess carried electroscopes up in a balloon expecting Earth's background radiation to fade with altitude. Instead it kept rising the higher he went, proving some of it was pouring in from beyond the atmosphere. He had discovered cosmic rays, and won the Nobel Prize in Physics in 1936.

— Victor Hess, Discovery of Cosmic Rays — 1912 balloon flights; Nobel Prize in Physics, 1936