Outburst by comet Holmes

Comet 17/P Holmes suffered an outburst in 1892, which led to its discovery then by Edwin Holmes. Causes for a cometary outburst are uncertain, but they might be due to solar heating after close passage around the Sun, or perhaps are due to a collision with another small unseen body. The left image shows comet Holmes' spherical dust coma that was produced after an outburst in October 2007, with the right image showing the comet after its obscuring coma is digitally filtered out. This filtering shows that the coma also hides several cometary fragments that drift away from the main nucleus at speeds of about 100 m/sec. White dots are background stars. These comet fragments also produce dusty streamers as they crumble and fade away, and sixteen such fragments were seen. This image was acquired at the Canada-France-Hawaii Telescope (CFHT) by Rachel Stevenson (UCLA) and colleagues, and a copy of their paper can be found at the arXiv preprint server.