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Wednesday, January 07, 2009

According to the most detailed measurements yet, scientists have discovered that our solar system, the Milky Way, is moving at 600,000mph, 100,000mph faster than originally thought.

The speedier rotation also means its mass must be similar to that of Andromeda, around 270 billion times the mass of the sun.

It means that the gravitational pull the Milky Way exerts on its neighbouring galaxies is stronger, meaning a collision would happen sooner than expected.

The Milky Way and Andromeda galaxies are the two largest in our cosmic neighbourhood, with the former 100,000 light years across, which is still only half the width of the latter.

Our solar system is around 28,000 light years from the centre of the Milky Way; Andromeda is around two million light years away.

The research, presented at the annual meeting of the American Astronomical Society in Long Beach, California, argues that the collision will happen around the same time our sun is due to burn up the last of its nuclear fuel, within the next seven billion years.

It is thought rather than planets and stars colliding, the two galaxies will merge to form a new, large galaxy.

Karl Menten, an astronomer at the Max Planck Institute for Radio Astronomy in Germany, and Mark Reid at the Harvard-Smithsonian Centre for Astrophysics in Massachusetts used a radio telescope called the Very Large Baseline Array (VLBA) to make precise measurements of the Milky Way as it moved through space.

"These measurements are revising our understanding of the structure and motions of our galaxy," said Dr Menten.

Gerry Gilmore, at the Institute of Astronomy at Cambridge University, who was not involved in the study, said: "The galaxies will be dramatically stirred up, but they are very squidgy, so they will stick together and eventually all the stars will die out, and it will become one huge, dead galaxy."


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