Planet ‘spotted’ in Andromeda galaxy

Astronomers believe they may have discovered the first planet ever detected in another galaxy. The new world was apparently glimpsed in the closest giant spiral galaxy to the Milky Way, Messier 31 in the constellation of Andromeda.

Phot of M31 by It lies an incredible 2.5 million light-years away – too far normally to be seen.

But it revealed itself thanks to a phenomenon called microlensing where the gravitational field of an object closer to Earth acts like a magnifying glass.

Amazingly, it has taken the astronomers five years to realise that they probably netted an extra-galactic planet. They observed a peculiar microlensing event while studying the Andromeda galaxy – which can be seen as a dim blur with the unaided eye – in 2004.

The international team, using the UK’s Isaac Newton Telescope on the Canary Island of La Palma, thought at the time that they had recorded a pair of stars orbiting each other.

But computer simulations and other calculations have persuaded them that they actually observed a star with a smaller, planet sized companion about six times bigger than Jupiter.

More than 300 so-called exoplanets have been found orbiting other stars in our own galaxy. And NASA has launched a $595 million spaceprobe called Kepler to watch 100,000 stars for signs of world like Earth.

Picture: A photo of the galaxy M31 in visible light. (Photo: John Lanoue).

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available.

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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