Timeline of other background radiation fields
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Timeline of other background radiation fields

• 1912 - Victor Hess discovers that the ionization of air increases with altitude indicating the existence of cosmic radiation
• 1949 - Herbert Friedman detects evidence for extrasolar X-rays
• 1962 - Riccardo Giacconi, Herbert Gursky, F. Paolini, and Bruno Rossi formally discover the X-ray background

The original article can be found at: http://en.wikipedia.org/wiki/Timeline_of_other_background_radiation_fields.
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