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Exclusive: New X-ray Movie Shows 10 Years of Milky Way Activity

A new X-ray movie of the Milky Way Galaxy shows stars erupting and black holes pulsating over a full decade of time.

The movie, obtained exclusively by, shows the sky blinking in ways optical telescopes can't see. While stars are often pretty steady in their emissions of visible light, some vary greatly in their X-ray emissions.

The data was gathered by NASA's Rossi X-ray Timing Explorer, launched in 1995. The movie is a product of NASA and MIT. It shows stars seeming to blink in and out of existence, while other sources remain constant.

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Invisible black holes and dense neutron stars turn on and off, or vary over time, as they suck material off companion stars. The on-phases, powered by gas under extreme gravity, last weeks or months. As the gas spirals inward, it is superheated, causing it to glow with X-ray radiation. Some sources disappear for months at a time in the X-ray view.

Others are steadier but grow brighter and dimmer depending on the flow of fuel.

Blue represents the most energetic X-rays; green, less energetic; and red, the least energetic. 

Blue sources are generally very massive, fast-rotating stars called pulsars that feed off companion stars. Red objects are typically lower-mass binary systems. Many of the steady sources are green. One of these, the familiar Crab pulsar, is at the far right.

The Sun is shown as a white circle moving through the scene.

The bright source in the center above the galactic plane is Scorpius-X1, the first X-ray source ever detected in the galaxy. Scientists think it is a neutron star.

A suspected black hole named Cygnus X-1 is an obvious bright source on the galactic equator, just to the left of the activity in the galactic center. At the center lurks a supermassive black hole that's about 3 million times as massive as the Sun.

The movie was created by Donald A. Smith (MIT), Michael Muno (UCLA), Alan M. Levine (MIT), Ronald Remillard (MIT), Edward Morgan (MIT) and Hale Bradt (MIT).  The data comes from the MIT-built All-Sky Monitor, one of three instruments on the Rossi Explorer.

  • See the Movie

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Robert Roy Britt
Rob has been producing internet content since the mid-1990s. He was a writer, editor and Director of Site Operations at starting in 1999. He served as Managing Editor of LiveScience since its launch in 2004. He now oversees news operations for the TechMediaNetwork's growing suite of technology, science and business news sites. Prior to joining the company, Rob was an editor at The Star-Ledger in New Jersey. He has a journalism degree from Humboldt State University in California.