They are small, like most early star-forming galaxies, measuring no more than 5,000 light-years in diameter. But unlike previous finds, these clusters weigh as much as the Milky Way, with a mass equivalent to about 200 billion suns. Scientists suspect dark matter played a key role in the galaxies' formation. They theorize that dark matter, which accounts for most of the mass in the universe, trapped pockets of hydrogen generated in the universe's birth. Stoked by dark matter's gravitational hands, the hydrogen began swirling, igniting the engines of star formation. Not only are the baby galaxies obese with stars. The broods whip around their galactic disks at a heady 275 miles per second. That's about twice as fast as grownup galaxies. Related Links: |
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