Clouds of positrons (see Section 15-4 and An Astronomer’s Toolbox 10-1) have been discovered near the center of the Galaxy. Search the Web for information about this discovery. When was it made? How...

Clouds of positrons (see Section 15-4 and An Astronomer’s Toolbox 10-1) have been discovered near the center of the Galaxy. Search the Web for information about this discovery. When was it made? How were they discovered? What is thought to be the origin of these particles? What happens when ordinary electrons and positrons collide?