Fig 1. Adaptive optics images of asteroid (21) Lutetia obtained at
the W.M. Keck Observatory. Here Lutetia is shown at 10 different
times during the night of 2008 Dec 2 UT, plus other times. Here the
scale is shown in arcseconds, a measure of angular size. These images
have been processed (deconvolved) to enhance clarity.
The light and dark markings across the surface are artifacts of the processing and are not real. The changing outline of the asteroid, not any surface markings, is used to derive the asteroid shape.
Photo credit: Dr. Benoit Carry (Paris Observatory), Dr. Al Conrad (Keck Observatory), and Dr. William Merline (Southwest Research Institute).