THE BIGGEST FORBUSH DECREASE IN 20 YEARS: Solar storms are supposed to make radiation go up, right? A severe solar storm on June 1st did just the opposite. The Oulu Cosmic Ray Station in Finland registered the biggest drop in cosmic radiation in more than 20 years: This is called a "Forbush Decrease," named after American physicist Scott Forbush who studied cosmic rays in the early 20th century. It happens when a coronal mass ejection (CME) sweeps past Earth and pushes galactic cosmic rays away from our planet. On June 1, 2025, a fast-moving CME crossed Earth's orbit and thinned our planet's radiation environment. Cosmic ray fluxes dropped as much as 25%. To find another Forbush Decrease this deep, you have to go all the way back to October 30, 2003, when CMEs related to the famous Halloween Storms were pummeling Earth.