Spotters await the comet of the century

Thousands of amateur astronomers are preparing their binoculars to watch what could be the brightest comet so far this century. Comet Hyukatake, discovered in January by a Japanese amateur, will be at its brightest by the end of this week, when it should be visible all night as a large, fuzzy patch a little smaller than the Moon.

Besides being exceptionally bright for a comet, it will also pass very close - in cosmic terms - to the Earth. On Saturday it will be just 10 million miles away, having travelled hundreds of millions of miles through space on an elliptical orbit around the Sun that has probably taken centuries. It will then pass 20 million miles from the Sun before disappearing below the plane of the Solar System.

Although some comets have proved disappointingly dim after predictions that they would light up the sky, experts are hopeful this will be different.

"It looks as though this is going to be very bright," said the noted astronomer Patrick Moore yesterday. "I don't think that it will be as big as the full moon, but part of that is because it is still approaching us. It will look more like a conventional comet - with a tail streaming behind it - next month, when it is moving away from us."

Comets are frozen bodies of gas, liquid and rocks a few miles across whose "tails" are created by streams vapourising as the Sun heats them up. The tail always points away from the Sun.

The comet is currently most visible in the early hours of the morning, after about 3am. It is best viewed using binoculars: "Telescopes don't have a wide enough field of view," said Mr Moore. But as the week progresses it will become brighter and more visible throughout more of the night as it moves towards the sky's North Pole.

Anyone wanting to see it should find a spot away from city lights and allow their eyes to adjust to the lower brightness of the stars. It should be possible to spot the comet using the star chart (see graphic).

Hyukatake is now expected to be the brightest comet for at least 20 years, and possibly since the turn of the century. It was discovered in January by Yuji Hyukatake, an amateur astronomer using a powerful pair of 6in binoculars. At that time it showed up only as a faint smudge of light against the background of stars, but will now probably remain visible until May.

But even before Hyukatake has come fully into view, astronomers are preparing for the arrival next year of Comet Hale-Bopp, which will make its closest approach to the Sun on 1 April. It could eventually be brighter than Hyukatake, according to experts who spotted it beyond Jupiter's orbit last summer.