On January 20, 2005 the Sun emitted cosmic rays of sufficient energy and intensity to increase radiation levels on the surface of Earth. This "Ground Level Enhancement" (GLE) was especially intense at South Pole and McMurdo, Antarctica. In fact the McMurdo increase was the largest observed at sea level since the famous 1956 GLE, which was the largest ever recorded.

For more information about neutron monitors, please visit the home page of the
Bartol Research Institute Neutron Monitor Program.