An early tea could be advisable today as the world may end at 6 p.m.

DON'T bother buying a ticket for tomorrow night's roll over Lotto jackpot. The world is going to end at around teatime this evening, if the numbers calculated by a 17th century Irish cleric are correct.

Archbishop James Ussher won great fame in his day for his system of chronology which identified 23rd October 4004 BC as the date of creation. But, borrowing a Jewish tradition which said the world would last 6,000 years, he went on to calculate that the curtain would come down on the whole production today.

Born in Dublin in 1581, Ussher was a towering intellect of his time, entering the just founded Trinity College at the age of 13. By the time of his death in 1656 he had amassed a library of 10,000 volumes. Nevertheless, his calculations appear to have been a mixture of astronomy, biblical chronology, intelligent guesswork and whatever he was having himself.

His creative accountancy embraced everything from solar and lunar calendars to Old Testament accounts of the ages of the patriarchs and emerged with the absolute certainty that the earth began on 4004 BC, at around 6 p.m.

Ireland's astronomers are celebrating Ussher's work this week with a public lecture in Armagh. With scant respect for his theories, they planned it for next Friday night.

But Prof Mark Bailey of Armagh observatory argues that since there was no year zero, Ussher's 6,000 years may not be up until next October.

He adds that there is little in the sky at the moment to support a doomsday scenario. Traffic is building up out there, however. Comet Hale Bopp is heading our way, and next January the Earth will pass through its meteor stream. By April, the comet will be at its closest, a mere 90 million miles away. For this and a few other reasons, Prof Bailey argues, next October may be more promising, in end of the world terms.

Ussher's latest successor, Archbishop Robin Eames, was out of the country and unavailable for comment yesterday. A spokeswoman said he was due to return sometime today and is not known to be concerned about his predecessor's prediction.

This is only the latest in a long line of end of the world prophecies, of course, and none of the prophets have hit the jackpot yet. If Archbishop Ussher's does join the roll over of unclaimed Armageddon dates, tomorrow night's Lotto will be worth more than £2.5 million.