Comet Hyakutake

Comet Hyakutake (formally C/1996 B2) was discovered by Hyakutake, on January 30, 1996. The comet made its closest approach to the Earth (~0.109AU) in March 1996, at which time it was a naked-eye object throughout the northern hemisphere. The comet reached perihelion on May 1, 1996.

The Ulysses spacecraft made an unplanned and unexpected pass through the tail[?] of the comet on May 1, 1996. Based on the Ulysses encounter, the comet's tail is known to have been at least 300 million miles long. Terrestrial observers found ethane and methane in the comet, the first time either of these gases had been detected in a comet.

External link: JPL Comet Hyakutake home page (http://www.jpl.nasa.gov/comet/hyakutake/)