2.4 APOD

For picture go to : http://apod.nasa.gov/apod/image/0711/cr_auger_big.jpg
For centuries astronomers have wondered where cosmic rays (energetic particles that begin in space and impinge on Earth's atmosphere and now the Pierre Auger Observatory in Argentina may have an answer. Auger suggests that 12 out of 15 ultra highhigh energy cosmic rays come from the direction of nearby active galactic nuclei (a compact region at the center of an active galaxy). These galactic centers emit large amounts of light and are probably feuled by a blackhole. The Auger Observatory believes that the highest energy rays are protons because any higher energy raywould be deflected by the Milky Way Galaxy's magnetic field and we wouldn't be able to figure out which direction the ray was coming from. The APOD picutre is of a ray striking Earth's atmosphere, with an active galaxy (Centaurus A) in the background as the galaxy from which the ray might have come.