Tuesday, September 14, 1999 Published at 00:59 GMT 01:59 UK
'Earth-sized planet' in deep space
The new planet is seen in the centre of the picture
by BBC News Online Science Editor Dr David Whitehouse
A chance alignment between two stars may have allowed astronomers to detect the first Earth-sized planet found outside our solar system.
In June 1998 observations made at the Mount Stromlo Observatory in Australia and the Mount John Observatory in New Zealand detected a star near the centre of our galaxy becoming abnormally bright.
The brightening occurred because of the so-called gravitational lensing effect. This happens when another star passes directly between the distant star and ourselves.
Its gravity acts like a lens bending and amplifying the light from the distant object. The observatories were looking for just such an event.
A detailed analysis of the data suggests the light-curve can only be explained if it has a planet orbiting it.
In the past few years astronomers have discovered about 20 planets orbiting some of the nearest stars to our Sun using different techniques.
All of them however have been massive and are probably more like the gas giant Jupiter than the small, rocky Earth.
This new planetary system would be unique in not having any gas giant planets. A detailed analysis has been submitted for publication in the Astrophysical Journal.
More recent observations of another star brightening suggest the same group of astronomers may have discovered a planet in a large orbit around two close stars.