Lunar Corona     Imaged in Ontario, Canada January '07 by Lauri Kangas (more images) . "My wife and I were starting our evening 4 km walk when I noticed the Moon and corona.  We turned around, headed back home and I took a few pictures.  It clouded up on and off for the next ½ hour.  The corona was very large at times with 3 distinct rings, although the 3rd ring was not as pronounced as it was when I actually got to take out the camera."   It is difficult to photograph a corona without overexposing the Moon's disk. Lauri took a shorter exposure to show the Moon and allowing the corona to be accurately measured. The red edge of the inner aureole was about nine Moon diameters or 4.5³ dia. The first red ring is 15 lunar diameters. IRIS simulations tell us that the droplets making this corona were therefore about 16 micron (6 X 1/10,000 inch) in diameter. Image ©Lauri Kangas , shown with permission.