In Messier 83, a barred spiral galaxy some 15 million light years away ("nearby," by cosmic standards), scientists have observed a "remarkable" outburst from a black hole -- its X-ray output has increased by a factor of 3,000. The above image on the left comes from optical data collected by the Very Large Telescope in Chile and shows the whole galaxy. On the right is a zoomed-in section combining data from NASA's Chandra and Hubble telescopes, with Chandra's X-ray data shown in pink and Hubble's optical data appearing in blue. The "ultraluminous X-ray source" (ULX) is the bright pink dot near the bottom of the right-hand image. The brightening that Chandra observed over a several-year period is one of the largest changes in X-ray output ever observed from a black hole.

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Image: NASA.