Astronomers have proposed a new explanation for the mysterious Cygnus Bubble, a vast cloud of ultra-high-energy gamma rays stretching thousands of light-years across the sky. While the bubble has generally been linked to the Cygnus X star-forming region, the new study argues that a microquasar more naturally explains its highest-energy emission. The results were published in a paper in The Astrophysical Journal Letters on July 21.