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Gamma ray bursts are the most powerful known explosions.
Gamma ray bursts are the most powerful known explosions in the Universe, so if one went off in our galactic back yard, it could be bad for life on Earth. Researchers working with NASA think that a massive extinction hundreds of millions of years ago could have been started by such an explosion. If a GRB went off only 6,000 light-years away, it would strip away much of the Earth's ozone layer, and expose all surface life to deadly levels of ultraviolet radiation from the Sun.
When you look at a galaxy, you can only see a fraction of its total mass. The rest is made up of mysterious dark matter, which only interacts through its gravity. This Dark matter usually extends as a giant Halo around the galaxy, extending much further than the visible stars. But researchers in the UK have found ancient fossil Galaxies concentrating Dark matter at their centres. These fossil Galaxies are the result of an entire Galaxy cluster collapsing into a single enormous galaxy. Why the Dark matter is concentrated is still a mystery.
In preparation for its return to flight, the Space Shuttle Discovery made the long slow journey atop its Crawler Transporter out to the launch pad yesterday. A small crack was discovered in the fuel tank insulation, but engineers didn't feel it was enough of a risk to delay Discovery from moving out to the launch pad. If everything goes well, Discovery will lift off on May 15, but a final report from the Columbia Accident Investigation Board could demand additional changes that would push the launch back.
The Chandra X-Ray Observatory has detected distant Galaxies going through a period of tremendous star formation, at the same time the supermassive black holes at their centres are packing on material. These extremely luminous Galaxies (and their black holes) went on this growth spurt more than 10 billion years ago, and they could be getting ready to turn into quasars - distant Galaxies that contain the largest and most active black holes in the Universe.
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