Universal History Archive/Getty Images
forplayday/Getty Images
buradaki/Getty Images
RomoloTavani/Getty Images
Five years ago, a galaxy 300 million light-years away got a lot brighter in telescopes, radiating ultraviolet, optical, and infrared light out into space. This year, the resurgent galaxy started emitting X-rays, indicating that its initial brightening was really just a warmup.
NASA, ESA, CSA, Ralf Crawford (STScI)
Pablo Carlos Budassi / Wikimedia Commons
NOAA
George Lepp/Getty Images