The two enormous gamma-ray bubbles emanating from the Milky Way’s center are called the Fermi bubbles.
Scientists identified the paired structures in data from NASA’s Fermi Gamma-ray Space Telescope, with the discovery announced in 2010. One bubble extends above the Galactic Center and the other below it, creating a roughly symmetrical structure that reaches about 25,000 light-years in each direction.
The bubbles emit gamma rays and are also visible at other wavelengths, including X-rays. Their sharp edges and energetic contents show that they are not ordinary clouds of stars or gas. Instead, they contain extremely energetic particles and likely record a major episode in the history of the Galactic Center.
Their precise origin remains an active area of research. Leading possibilities include an outburst from Sagittarius A*, the supermassive black hole at the Galaxy’s center, or a powerful burst of star formation. The name refers to the Fermi telescope, not to Compton, Hubble, or Einstein; those names are associated with other astronomical instruments or scientists.