Comet Hyakutake.

Comet Hyakutake.

Courtesy of NASA

http://commons.wikimedia.org/wiki/Image:060227comet.jpg


The "Great Comet" of 1996, Hyakutake. The stunning discovery of X-ray emissions from the visitor was a milestone in comet science, as was the discovery that the comet's coherent and filamentary ion tail spanned more than 350 million miles.