The planets are lining up but there is nothing to fear, said local astronomer Eddie McGonagle.

The phenomena, which happens roughly every 20 years, can be seen by looking west where five planets - Mercury, Venus, Mars, Jupiter and Saturn - can be seen in a clump by the naked eye.

Astrologers attach deep significance to planetary alignment but Mr. McGonagle said there is nothing mystical or frightening about the line-ups.

"All of the prophets of doom and gloom are just indulging in absolute ignorance," he said.

However, he said one scientist got caught up in the panic and wrongly predicted a 1962 convergence of planets would exert enough gravity to set off severe earthquakes in the San Andreas fault.

The spectacle will be seen from all over the globe but Mr. McGonagle said the best views here are from positions which give a long horizon.

He recommends the South Shore and Dockyard, although he says binoculars will be useful for Mercury, which will set quite early but the other planets will remain above the horizon for some time.

He said: "From now until about mid-May these five planets will be seen, after sunset, in a fairly straight line reaching from the Sun's setting position on the horizon to almost our zenith.

"Venus, being the brightest, appears first and Jupiter is the bright object almost overhead.

"During April and May the planets change their positions, as if in a dance, to form some of the nicest groupings that will be seen this century.

"It's well worth watching. On May 5, 6 and 7 this particular hoe-down will see a tight set of Mars, Venus and Saturn cavorting between Jupiter, above and a naked eye Mercury below.

"Another week will see the crescent Moon repeating her 'skip-too-my-loo' past the planets as she joins Mars and Venus for another binocular spectacle.

"This is a sign for Mercury and Saturn to head for the horizon - the dance is over for them."

McGonagle said the last planetary grouping of this size was only two years ago. In May 2000 the Sun and the Moon but we were on the opposite side of the Sun and the impact was lost.

He said the groupings of 2040 and 2060 will be difficult to see although the 2100 grouping will be good.

He said the planets came together occasionally just as inside runners in a race track would overlap with outside runners in a perpetual race.