Skywatchers throughout the Northern Hemisphere report that comet Ikeya-Zhang, the brightest since Hale-Bopp five years ago, is a remarkable sight even under city lights. The comet, described in glowing terms by many observers, should be visible to the naked eye throughout most of April.

Only a couple comets each decade are this easy to see.

Ikeya-Zhang made its closest approach to the Sun, called perihelion, on March 18. In the days that followed, people who found the comet in the northwest evening sky saw a bright and bluish-white, starlike nucleus surrounded by a fuzzy cloud of dust and gas, called the coma.

The comet's tail streaks away from the Sun, as always, pointing nearly straight up from the horizon now because of the comet's position in relation to the Sun as seen from Earth.

Comets shine brightly because some of their gas and dust burns off when they are near the Sun. This halo of material reflects sunlight.

Although Ikeya-Zhang is now moving away from the Sun, it is approaching Earth, so any fade-down is probably going to be slow to occur.

On April 1, the comet was equally distant from the Sun and the Earth at 56 million miles. It will continue to draw nearer to Earth until April 29, when it will be 37.6 million miles away (60.5 million kilometers).

Our latest "guesstimate" for Ikeya-Zhangs brightness in the coming weeks is for it to gradually dim to about fourth magnitude by mid-April and to around fifth magnitude by the beginning of May. Those blessed with very dark skies might be able to continue following the comet with just their unaided eyes until about the middle of May.

Of course, the comet could dim much more rapidly. Or, conversely, a sudden unexpected flare-up could also occur. But these are extreme possibilities. So far, the comet has performed very well, and pretty much as expected, and it is likely to continue to delight Northern Hemisphere observers for a few more weeks.

Again, the darker your observing site, the better view you'll get of the comet. Viewing during the second and third weeks of April will be aided by the fact that the Moon will be mostly out of the way.

Ikeya-Zhang was discovered by Kaoru Ikeya of Japan and Daqing Zhang of China on Feb. 1, 2002. It is thought, however, to be the return of a comet first discovered in 1661.