There was a new star in the sky over the island of La Palma last May. The British astronomers who were monitoring the phenomenon observed it again this January. Yet its appearance was no surprise - the scientists had created the star in the first place, writes Steve Farrar.

The proof-of-concept tests were carried out by a team from Durham University, led by Richard Myers and Paul Clark, who aim to project a constellation of "artificial stars" into the atmosphere to boost the capability of terrestrial telescopes.

The astronomers want to cancel out the blurring impact of atmospheric turbulence using a technique called adaptive optics.

This involves grabbing a stream of snapshots of a bright star that happens to sit in the sky near the object being studied. The way the air above the telescope distorts the star's light is analysed in real time and then used to correct the target image.

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The Durham team has trialled a prototype system at the Anglo-Dutch William Herschel Telescope that works even when a bright star is not found conveniently close to the object being studied.

They used a commercially available, high-powered, pulsed laser projected into the sky from the telescope. The laser was focused at an altitude of 5km-20km, to produce an "artificial star" where air molecules scattered the light back to earth. Despite the technical challenge, results have been positive.

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If three to five such stars could be projected in a ring, the enhanced telescope could compensate for the uneven layers of turbulence and gain a large field of vision. Astronomers could then analyse the spectra of very faint objects, such as distant galaxies, and hence explore the structure of the early universe.

A bid for a more permanent set-up at the William Herschel Telescope is to be considered by British and Dutch funding bodies.