Artist's version of the ACE spacecraft.
Click on image for full size
Courtesy of NASA
News story originally written on June 4, 1999
Scientists have found where cosmic rays come from! The rays are made of atoms. These atoms are flying through space at speeds close to the speed of light. Until now, scientists didn't know where they came from.
Using the Advanced Composition Explorer (ACE), NASA found that the atoms have to be part of gas and dust in space. They once thought that the atoms came from a supernova, which is an exploding star. Instead, they found the atoms are just floating around! The energy from the supernova helps the atoms reach the speed of light.
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