Astronomers discover a new type of object — huge bubbles of gamma rays stemming from the heart of the galaxy.
"You have to ask where could energy like that come from," said astronomer Doug Finkbeiner, with the Harvard-Smithsonian Center for Astrophysics.
Theory One: a burst of star-formation at the center of the galaxy generated short-lived massive stars with energetic winds that blasted high-energy particles out into space.
Read More at Discovery News: History of Space