Caption: This "skymap," generated in 2009 from data collected by the IceCube Neutrino Observatory, shows the relative intensity of cosmic rays directed toward the Earth's Southern Hemisphere. Researchers from the University of Wisconsin-Madison and elsewhere identified an unusual pattern of cosmic rays, with an excess (warmer colors) detected in one part of the sky and a deficit (cooler colors) in another. A similar lopsidedness, called "anisotropy," has been seen from the Northern Hemisphere by previous experiments, but its source is still a mystery. Possible explanations include the remains of an exploded supernova, such as the nearby supernova remnant Vela located near the red hotspot seen in the skymap, or the interstellar magnetic fields near Earth.
Photo: courtesy IceCube collaboration, UW-Madison
Date: 2009
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