ヘール・ボップ彗星
The small size of the nucleus (Halley's Comet is about across, while Comet Hale–Bopp was about across) implies that Hyakutake must have been very active to become as bright as it did. Most comets undergo outgassing from a small proportion of their surface, but most or all of Hyakutake's surface seemed to have been active. The dust production rate was estimated to be about 2 kg/s at the beginning of March, rising to 3 kg/s as the comet approached perihelion. During the same period, dust ejection velocities increased from 50 m/s to 500 m/s.