Theodor Wulf (28 July 1868 – 19 June 1946) was a German physicist and Jesuit priest who was one of the first experimenters to detect excess atmospheric radiation.

Theodor Wulf became a Jesuit priest at the age of 20, before studying physics with Walther Nernst at the University of Göttingen.

He designed and built an electrometer which could detect the presence of energetic charged particles (or electromagnetic waves).

[3] Energy was coming from outside the Earth's atmosphere and being detected by his device; this radiation was from cosmic rays.

He published a paper in Physikalische Zeitschrift detailing the results of his four days of observation on the Eiffel Tower.