An international team of astronomers has observed the perfect cosmic storm: the most powerful collision of two galactic clusters ever recorded.

The scientists who discovered the collision likened it to two high-pressure weather fronts colliding to create hurricane-like conditions. Only in this case, whole galaxies can be thrown from their paths. As the two clusters hit each other head on, the impact created an enormous shock wave of superheated gases and plasma that rolled out into space.

Galactic clusters are the largest gravitationally bound structures in the universe: each cluster contains thousands of galaxies and millions of stars.

The cosmic light show was spotted with the European Space Agency's XMM-Newton observatory. The super cluster involved is Abell 754, in the constellation Hydra.

Team leader Dr Patrick Henry of the University of Hawaii said: "Here before our eyes we see the making of one of the biggest objects in the universe. 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.

Although the super cluster has been known for many years, it is only with the detailed analysis of data now available that scientists can say what actually happened during the collision.

"One cluster has apparently smashed into the other from the 'northwest' and has since made one pass through," said Dr Alexis Finoguenov of the Max-Planck Institute for Extraterrestrial Physics.

"Now, gravity will pull the remnants of this first cluster back towards the core of the second. Over the next few billion years, the remnants of the clusters will settle and the merger will be complete."

The Milky Way is also part of a galactic cluster. We are heading for the Virgo cluster, it seems, and will ram straight into it in around two billion years time. Make a note in your diaries. ®

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