At the center of the Milky Way, a giant stellar cauldron boils. Massive stars are born and die there: each death is a supernova explosion, hurling clouds of charged particles into space. These particles, accelerated to nearly the speed of light, collide with gas and radiation, emitting gamma-ray light — the most energetic in nature. Thus, above the plane of the galaxy, two bubbles tens of thousands of light-years tall are puffed up, like steam bubbles above boiling water. The Fermi telescope spotted them back in 2010, but only now has a computer model shown that the black hole has nothing to do with it. The vigorous life of ordinary stars is enough. Moreover, different parts of the bubbles glow in their own way: it depends on how particles lose energy. This gamma-ray “rainbow” is called a spectrum. The biggest surprise: the bubbles are not hot gas, but the glow of particles accelerated to nearly light speed. And the simulation also predicted: wherever there is gamma-ray glow, there should be radio waves and X-rays as well. Now astronomers know where to point their telescopes.