Reconstructed images showing the progression of the 2009-2010 eclipse of Epsilon Aurigae. The eclipse occurs once every 27.1 years and happens when a F-type star is obscured by a B-type star that is enshrouded in a large disk of opaque material. The pre-eclipse observations in 2008 (left) show the F-star as a nearly uniformly illuminated 2.27 milliarcsecond circle. The November 2009 observation (center) shows the shadow of the disk (outlined in a white ellipse) around second contact and the December 2009 observations (right) show that nearly 50% of the stellar surface is obscured by the eclipsing object.
John D. Monnier, University of Michigan