Hale-Bopp's Hoods
Explanation : Comet Hale-Bopp is spinning. The nucleus of the comet is a dirty snowball about 25 miles in diameter that spins about once every 12 hours . As Comet Hale-Bopp spins, parts of the comet's surface shoot away in jets. Ejected material therefore makes rings, which appear in above photograph as “ hoods ” in the coma . Even though the central part of Comet Hale-Bopp 's coma is quite condensed, the nucleus is not visible. Comet Hale-Bopp is now headed south, away from the Sun , and is getting dimmer . At its brightest last week, it was even brighter than Comet Hyakutake was last year, although with a less prominent tail . Comet Hale-Bopp will still be easily visible to northern observers for several weeks in the northwest sky after sunset .