The nucleus which is 1.2 miles (2 km) long and only 0.25 miles (0.4 km) wide at its narrowest section resembles a dog bone. In fact, it looks like a contact binary which is an object that consists of 2 main masses held together by gravity. The smooth narrow section being made up of fine material around the contact point. Recent observations suggest this shape may be common among comet nuclei. Comet 8P/Tuttle is known to have this shape and even 1P/Halley may be another example. This  is just conjecture on my part and much better analysis will come from the EPOXI team in the coming days.

Congratulations to the EPOXI team for a job well done not  only with the Hartley 2 flyby but also with the Tempel 1 encounter and the cruise phase extrasolar planet observations!

Montage of 5 images taken by the EPOXI s/c as it flew past the nucleus of 103P/Hartley 2. Credit: NASA/EPOXI Team/JPL.

Carl Hergenrother