New comet may delight in late March.

Japanese amateur astronomer Yuji Hyakutake knows how to handle a pair of binoculars. Last Christmas, he used his high-powered optics to discover a faint comet. On Jan. 30, with a second discovery, he truly hit pay dirt.

Astronomers predict that the comet he spied that day will venture within 14.5 million kilometers of Earth on March 25, then head toward a close encounter with the sun on May 1. The combination of events may make the comet visible to the naked eye for the better part of a month, beginning in late March. At its most luminous, it could rival the brightness of the star Betelgeuse.

A close encounter with either the sun or Earth brightens a comet's appearance, but "it's unusual to have a close approach to both," says Brian G. Marsden, head of the Central Bureau for Astronomical Telegrams in Cambridge, Mass.

Hyakutake reported the new find, officially named 1996 B2 but more commonly referred to as Comet Hyakutake, in a Jan. 31 circular of the International Astronomical Union.

Skywatchers in the Northern Hemisphere are expected to have a clear view of the comet because it will initially appear high in the sky, near the north celestial pole, all night. "During the first few weeks of April, the comet should be relatively easy to observe," says astronomer James V. Scotti of the University of Arizona in Tucson.

Although Comet Hyakutake may dim as it dives south and moves away from Earth, astronomers expect the icy body to brighten again by May 1 as it ventures within 32 million km of the sun. Sunlight vaporizes icy material on a comet's surface. This vapor drags dust out along with it, boosting a comet's brilliance by reflecting more sunlight. Some comets visiting the inner solar system for the first time expel their reserves of water-ice before they near the sun. Because no one knows whether Comet Hyakutake is a first-time visitor, Marsden says, there's no guarantee that it will dazzle skywatchers next month.