The biennial fly-by of the planet Mars is causing quite a stir. Dick Ahlstrom, Science Editor, outlines its significance.

The Red Planet is looming large in southern skies each evening and tomorrow it makes its closest pass of the Earth in human history.

In one way its close approach is much ado about nothing. The two planets' orbits come into close proximity every 26 months so the Red Planet if nothing else is a regular visitor.

What makes Wednesday, August 27th, 2003, special is that it is so very close to us, relatively speaking, of course.

At 10.51 a.m. Irish time tomorrow Mars will be less than 34.65 million miles away, the closest it has been for 60,000 years.

If you miss the big event then be prepared for a wait to see the like again. The next time the two planets get that close won't be for 284 years.

The two planets are in "opposition", a term describing the fact that they both lie on the same side of the sun and in line, explains Kevin Nolan, physics lecturer and Mars-watcher of the Institute of Technology, Tallaght.

It happens every 26 months because it takes much longer, 687 days, for Mars to complete a single orbit of the sun or Martian year compared to the 365 days of an Earth year. We go round our shorter orbit in half the time and complete two orbits before an opposition with Mars occurs.

Whether these events are a big deal depends on your perspective.

Professional astrologer Pemo Theodore believes recent severe weather and forest fires across Europe can be attributed to our close proximity to the Red Planet and an overabundance of "Mars energy".

"Whenever something changes or happens in the sky it has an effect on Earth," says Theodore. "We look in the sky to see what reflections are happening on the planet. We have to deal with Mars energy."

Mars can represent aggression and war, she says. "It also rules heat and fire, and I think that is what has happened. The hot weather and the fires in Portugal and France are associated with that."

Also a teacher of astrology, Theodore describes herself as a "Jungian astrologer", using it to look at the psychological effects on individuals rather than using it to predict the future. "I would look at the horoscope as the map of the psyche," she says.

Astrologer Austin Byrne also believes these oppositions have a powerful "psychological effect" on human activity. "The close opposition of Mars is always going to have an astrological significance," he says.

When Mars exerts its influence then aggressive behaviour, wars, drive, initiative, "all the things that are a part of Mars", come to the fore, he says. "It is a time when people are more edgy."

Oppositions can be "favourable" or "unfavourable", and this happens to be a favourable one. "We would see this as a time that people would be very reactionary and responsive to things they felt they had to do something about," explains Byrne.

Mars carries its traditional bellicose influence, however, and is associated with wars and disquiet, he notes. "Unfortunately it is rather easy to say that because the Earth is in political turmoil."

Astronomers, too, are excited by the closest Mars-Earth opposition to occur since before Neanderthal Man stalked the planet and the Woolly Mammoth and Sabre-Toothed Tiger roamed.

"They are regular events, but what is significant this time is they are so close," says Kevin Nolan. For this same reason Mars is being peppered by space probes, with half-a-dozen launches this year. It takes less time and energy to reach Mars when they are so close, so the planetary alignment is just right for a mission to Mars, he says.

It is also good news for amateur astronomers, he adds. "The planet is much bigger in the telescope now because it is so close compared to other oppositions." Its striking ruddy colour also makes it an easy target to find in the night sky.

Astronomy Ireland has planned more than a dozen free public Mars watches for tomorrow night.

They take place at 9.30 p.m. at venues including Boyle, Carlow, Castlebar, Clonmel, Cork, Downpatrick, Dublin, Kerry, Mullingar, Nenagh, Sligo, Waterford and Wexford. Further details are available by dialling Astronomy Ireland at 01-8470777 or checking its website at: www.astronomy.ie