Astronomers have discovered evidence that a planet like the Earth is forming around another star. The find was made with Nasa’s Spitzer space telescope.

Scientists say conditions around the sun-like star, 424 light-years away, are perfect for a rocky planet where life could one day exist.

Their heat-seeking telescope, which views the universe in the infrared part of the spectrum, detected a huge belt of warm dust swirling around the star in a system called HD 113766 in Centaurus.

With an age of ten million years, the star is at the right stage to form rocky worlds and the amount of dust is enough to build a planet the size of Mars or bigger.

Spitzer showed that the mix of materials in the dust are also just the right ingredients to make terrestrial planets. And the planet factory lies slap in the middle of what astronomers call the star’s “habitable zone”, just as the Earth is in the same zone around the sun.

The discovery team’s leader, Dr Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory, in Maryland, will officially announce the find at the American Astronomical Society Division for Planetary Sciences meeting at Orlando, Florida, next week. A report will also appear in the Astrophysical Journal.

In August evidence was reported from Spitzer of water raining on to a new solar system forming around another star. Spitzer had previously checked out an exoplanet’s windy weather, and also identified a planet as glowing like a cinder.

Of the newest discovery, Dr Lisse said: “The timing for this system to be building an Earth is very good. If the system was too young, its planet-forming disk would be full of gas, and it would be making gas-giant planets like Jupiter instead. If the system was too old, then dust aggregation or clumping would have already occurred and all the system’s rocky planets would have already formed.”

He added: “The material mix in this belt is most reminiscent of the stuff found in lava flows on Earth. It contains raw rock and is abundant in iron sulphides, which are similar to fool’s gold. It is fantastic to think we are able to detect the process of terrestrial planet formation. Stay tuned — I expect lots more fireworks as the planet in HD 113766 grows.”

Picture: An artist’s impression of the dust ring around HD 113766. Credit: NASA/JPL-Caltech/JHUAPL.

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