This animation shows an artist's rendition of the cloudy structure revealed by a study of data from NASA's Rossi X-Ray Timing Explorer satellite. At the hearts of most big galaxies, including our own Milky Way, there lurks a supermassive black hole weighing millions to billions of times the sun's mass. As gas falls toward a supermassive black hole, it gathers into a so-called accretion disk and becomes compressed and heated, ultimately emitting X-rays. The centers of some galaxies produce unusually powerful emissions that exceeds the sun's energy output by billions of times. These are active galactic nuclei, or AGN. The study is the first statistical survey of the environments around supermassive black holes and is the longest-running AGN-monitoring study yet performed in X-rays. Scientists determined various properties of the occulting clouds, which vary in size and shape but average 4 billion miles (6.5 billion km) across -- greater than Pluto's distance from the sun -- and twice the mass of Earth. Video and script credit: NASA's Goddard Space Flight Center/Wolfgang Steffen http://www.nasa.gov/multimedia/videogallery/index.html#.Uw0xBfRdUeI Subscribe to The Daily Conversation null Facebook http://www.facebook.com/thedailyconversation Google+ https://plus.google.com/100134925804523235350/posts Twitter http://www.twitter.com/thedailyconvo