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Wednesday, 16 August, 2000, 17:03 GMT 18:03 UK
No light from nearby planet
Tau St Andrews
At the time, it was dubbed the Millennium Planet
By BBC News Online science editor Dr David Whitehouse

The first ever observations of light from a planet orbiting another star were incorrect, say astronomers.

Researchers in Scotland have admitted they have been unable to confirm their discovery.

The team at St Andrews University caused a sensation last year when they reported that they had detected light reflected off a planet outside our Solar System - a so-called exoplanet.

But one of the scientists, Dr Andrew Collier-Cameron, has revealed that "by sheer bad luck" they had been misled by "random noise" in the data they had been studying.

Exceptional body

The story centred on the star Tau Boo, around which a Jupiter-class planet is known to orbit.

Detecting light from such a planet would have been a breakthrough. Astronomers hoped to analyse the light, deduce the planet's properties, and possibly look for evidence of life.

But speaking at the International Astronomical Union (IAU) General Assembly in Manchester, UK, Dr Collier-Cameron said that follow-up observations of the star had failed to confirm the initial results.

Other researchers suggested the group had been premature in revealing their findings.

However, some astronomers are relieved at the news. They said that if light from the Tau Boo planet had been detected, it would have indicated an exceptional body. That it has not means the planet must have more usual dimensions and reflective properties.

According to Mark Marley, of New Mexico State University, US, astronomers have learned from this episode. "We need new and better observations," he said. "But with modern equipment the prospects are bright."

Advances needed

The largest exoplanets circling nearby stars might just be within the vision of the Hubble Space Telescope but their close proximity to bright parent suns makes detection virtually impossible - they are lost in the light.

To observe the light from exoplanets would require instruments that are significantly better than those currently in use, said Dr Neville Woolf, of the Steward Observatory, US.

"They would have to be about 10,000 times better than our best telescopes," he added.

A possible solution to this problem is to look for the planets in the mid-infrared region of the spectrum where the planet may become 1,000 times brighter. However, at these wavelengths, current telescopes cannot see such fine detail.

Dr Woolf is devising techniques to detect bands of dust circling nearby stars. After that astronomers could concentrate their search for planets around stars that do not have much dust.

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See also:

22 Nov 99 | Sci/Tech
Light detected from distant planet
16 Nov 99 | Sci/Tech
Extrasolar planet detected
07 Aug 00 | Sci/Tech
Nine new planets found
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