March 27, 1997: Completing an unprecedented yearlong study of Comet Hale-Bopp with two NASA observatories, including the Hubble telescope, astronomers report that they are surprised to find that the different ices in the nucleus seem to be isolated from each other. They also have seen unexpectedly brief and intense bursts of activity from the nucleus during the monitoring period. The Hubble observations suggest that the nucleus is huge, 19 to 25 miles (30 to 40 kilometers) across.
Here are a series of Hubble telescope observations of the region around the nucleus of Hale-Bopp, taken on eight different dates since September 1995. They chronicle changes in the evolution of the nucleus as it moves ever closer to, and is warmed by, the Sun.See the rest: