This is one of the latest images of comet Hale-Bopp. Notice the intense tail Click on image for full size Courtesy of National Astronomical Observatory of Japan

Hale-Bopp continues to offer new surprises as two astronomers report of their study of the comet. Using the Hubble Space Telescope and the International Ultraviolet Explorer, the astronomers did a year-long study on Hale-Bopp to find that their are distinctly different ices in the comet's nucleus, the nucleus is huge, and the nucleus is extremely active.

The comet's nucleus seems to be erupting upon itself. Astronomers witnessed the comet spew out dust in intermittent bursts. The surface seems to be an incredibly dynamic place, with 'vents' being turned on and off as new patches of icy material are rotated into sunlight for the first time.

The nucleus' structure itself is more complex than astronomers had thought. Astonomers theorized that trace gases were contained within water ice. According to Hubble Space Telescope observations, however, Hale-Bopp's nucleus has trace components contained within their own ice structure, with water ice remaining separate and uniform.

In addition, the nucleus is tremendously large. Astronomers have estimated Hale-Bopp's nucleus to be 19-25 miles (30-40 kilometers) in diameter. Comets are thought to have a nucleus of about 3 miles (5 kilometers) on average.