Comet Hale-Bopp, a 40km-wide "dirty snowball" of mud and ice has already delighted astronomers by producing a bright show that has far outdone two predecessors in the past 10 years, Halley's Comet in 1986 and Comet Hyukatake last year.
"It's like London buses," said Duncan Copp, of Mill Hill Observatory near London yesterday. "You wait for years and then they all turn up at once."
Unlike its predecessors, which were hard to see without telescopes, Hale- Bopp should be easily visible after dark and before dawn with the naked eye, though Dr Copp suggests that those wanting a really good view should take a pair of binoculars, as they offer a wider field of view than a telescope.
"To view it in the evening, you want an unobstructed view of the north- west horizon," he said. "You can see it at any time after twilight. It is an impressive sight, though people could be disappointed if they don't get away from lights." Just before sunrise it should be visible on the north-east horizon.
Those who do take the trouble will see the bright nucleus, made of a frozen conglomerate of ice and interstellar dust, and the tail, consisting of gases boiling off from the nucleus as it nears the Sun on its 8,000-year round trip. For that reason, the tail points away from the Sun, rather than in the direction of the comet's travel.
Its closest approach to the Earth will be on 22 March, when it will be 123 million miles away from us, further than we are from the Sun, and its closest approach to the Sun occurs on 1 April, when it will be 85 million miles away. (The Earth is 93 million miles from the Sun.)
Those keen to photograph the comet need a camera whose lens can be set to an exposure of minutes, and should use fast film - at least 400 ASA - and a tripod.