Hold tight! Milky Way poised to collide with nearest galaxy sooner than first predicted

Hold tight! Milky Way poised to collide with nearest galaxy sooner than first predicted

By Daily Mail Reporter
Last updated at 11:11 AM on 06th January 2009

The Milky Way is set to crash violently into its nearest galaxy Andromeda sooner than scientists originally predicted.

Researchers found they had previously miscalculated the mass of our galaxy when making their most detailed mapping of the Milky Way.

A team lead by Mark Reid of the Harvard-Smithsonian Centre for Astrophysics in the U.S. measured the Milky Way in a three-dimensional way and found that it is actually 15 per cent larger in breadth than Andromeda. More importantly, it is denser, with 50 per cent more mass.

Being bigger means the gravitational pull between the Milky Way and Andromeda is stronger, meaning the collision between the two galaxies will take place earlier than initially thought.


Scientists mapped the Milky Way in a more detailed, three-dimensional way and found that it is 15 per cent larger in breadth than Andromeda

However, people shouldn't be worried about the event happening any time soon - as any collision would still be at least two to three billion years from now.

The new findings were presented at the American Astronomical Society's convention in Long Beach, California.

Dr Reid, author of the findings, said: 'Previously we thought Andromeda was dominant, and that we were the little sister of Andromeda.

'But now it's more like we're fraternal twins.'

Dr Reid and his colleagues used a large system of 10 radio telescope antennas to measure the brightest newborn stars in the galaxy at different times in Earth's orbit around the sun.

They made a map of those stars, not just in the locations where they were first seen, but an additional dimension of time - something which hasn't been done before.

With that, Reid was able to determine the speed at which the spiral-shaped Milky Way is spinning around its centre.


A bigger Milky Way means that it could be crashing violently into the Andromeda galaxy (above) sooner than predicted

That speed - about 568,000mph - is faster than the 492,000mph that scientists had been using for decades and represents about a 15 per cent jump in spiral speed.

The old number was based on less accurate measurements and this is based on actual observations, Reid said.

Once the speed of the galaxy's spin was determined, complex formulas that end up cubing the speed determined the mass of all the dark matter in the Milky Way.

And the dark matter - which we cannot see - is by far the heaviest matter in the universe. So that means the Milky Way is about one-and-a-half times the mass had astronomers previously calculated.

Therefore the long-forecast collision between the neighbouring galaxies is not only poised to happen sooner, but it is less likely to be a glancing blow, scientists said.

Source: http://www.dailymail.co.uk/sciencetech/article-1106383/Hold-tight-Milky-Way-poised-collide-nearest-galaxy-sooner-predicted.html