A segment of the nucleus of comet Hartley 2 illuminated by the sun.. A distinct cloud of individual particles is visible
Particles swirling in a "snow storm" around the nucleus of comet Hartley 2. The largest of the particles range from the size of a golf ball to a basketball. And yes, that's ice out there, not dust, according to NASA.
The photograph on the left is the full image of comet Hartley 2 for context, while the image on the right was enlarged and cropped.
Icy particles traveling with the nucleus were described by astronomers as akin to fluffy "snowballs" about 1 inch to 1 foot across.
The star moving through the background is marked with red. The icy particles are marked in green, blue and light blue.
This 3-D image shows the entire nucleus of Hartley 2 with jets and an icy particle cloud. Circles have been added to highlight the location of individual particles.
Infrared scans of comet Hartley 2 show carbon dioxide, dust, and ice being distributed in a similar way and emanating from apparently the same locations on the nucleus.
This image shows the nuclei of comets Tempel 1 and Hartley 2, as imaged by NASA's Deep Impact spacecraft (Tempel 1 is five times larger than Hartley 2.