Monterrey Lunar Corona
April 16, 2008
The photo above showing a magnificent lunar corona was captured on December 21, 2007 from near Monterrey, Mexico. On this first night of winter, my intention was to observe Mars with fellow members of the Sociedad Astronomica del Planetario Alfa, but the captivating and colorful corona diverted my attention to the Moon in a waxing gibbous phase. As thin, mid-level clouds passed over us, moonlight was diffracted around the edges of the droplets contained within these clouds. We noticed that the luminosity and intensity of the colors changed as the clouds moved in front of the Moon. This was due to the fact that -- larger droplets cause smaller diffraction angles and so a smaller "tighter" corona.
Photo details: Canon PowerShot A530 camera (set to manual), ISO 800, exposure times from 0.5 to 3 seconds, both hand-held and tripod. Twenty images have been merged to show the Moon and the coronal rings. The palm in the foreground was pictured later. Here in Monterrey, we call this desert plant a "Yucca," or simply "palma" (Yucca filifera).