NASA - National Aeronautics and Space Administration

Scientists have now officially witnessed the perfect cosmic storm. Thanks to the European Space Agency's XMM-Newton observatory, they watched a nearby head-on collision between two galaxy clusters. The clusters smashed together thousands of galaxies and trillions of stars in one of the most powerful events ever witnessed.

Cosmic Head-On Collision: galaxy clusters collide like two high-pressure weather fronts and create hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space. Credit: NASA

Remarkably similar to violent storms on Earth, the galaxy clusters collided like two high-pressure weather fronts and created hurricane-type conditions. The event tossed galaxies far from their paths and churned shock waves of 100-million-degree gas through intergalactic space.

This unusual view adds to the theory that the universe was built from the "bottom up." That it formed as the result of constant mergers of smaller galaxies and galaxy clusters into one larger one.

X-ray Brightness Map: This map shows "surface brightness" or how luminous the region is. The larger of the two galaxy clusters is brighter, shown here as a white and red spot. A second cluster resides about "2 o'clock" from this, shown by a batch of yellow surrounded by green. Credit: ESA/ XMM-Newton/ Patrick Henry et al.

"Here before our eyes we see the making of one of the biggest objects in the universe," said team leader Dr. Patrick Henry of the University of Hawaii. "What was once two distinct but smaller galaxy clusters 300 million years ago is now one massive cluster in turmoil. The AOL takeover of Time-Warner was peanuts compared to this merger," he added.

The forecast for the new super-cluster is clear and calm, now that the worst of the storm has passed. Galaxy clusters are the largest gravitationally bound structures in the universe, containing hundreds to thousands of galaxies. Our Milky Way galaxy is part of a small group moving toward the Virgo Cluster. We are destined for a collision in a few billion years.

Image Right: The XMM-Newton satellite observed the actual event. Scientists at the Max-Planck Institute for Extraterrestrial Physics in Germany worked with Dr. Henry on the scientific results. Credit: ESA.

As for the cluster, Abell 754 in the constellation Hydra, scientists have known about it for decades. But for the first time, scientists created a complete "weather map" of it and can make forecasts. The map contains information about the temperature, pressure and density of the new cluster.

The observation shows the largest structures in the universe are still forming. Abell 754 is relatively close to Earth, about 800 million light years away. The construction boom may be over in a few more billion years, though. A mysterious dark energy appears to be accelerating the universe's expansion rate. This means objects are flying apart from each other at ever-increasing speeds, and clusters may eventually never have the opportunity to collide with each other.

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NASA Goddard Space Flight Center