Something big is going on at the center of the galaxy, and astronomers say they don’t know what it is.
Astronomer Doug Finkbeiner, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, used NASA's Fermi Gamma-Ray space telescope to discover two giant gas energy “bubble” structures extending 25,000 light years up and down from each side of the galaxy and containing the energy equivalent to 100,000 supernova explosions.
So far researchers’ best guess is that the bubbles were created by an eruption from a huge black hole at the center of our galaxy. Another theory is that they are fueled by star births and deaths, also at the center of the galaxy.
The material is not believed to be so-called “dark matter” because the gas bubbles have sharp, well-defined edges whereas dark matter would be expected to be more diffused.