After its closest approach to Earth, Rosetta looked back and took a number of images using the OSIRIS Narrow Angle Camera (NAC). This particular image was acquired 15 November 2007 at 03:30 CET. The image is a colour composite of the NAC Orange, Green and Blue filters. At the bottom, the continent of Australia can be seen clearly.
This page is no longer updated. The Library of Congress has a delightfully done, in-depth "Today in History" here: