April 3, 2009
Leonardo's Light
image by Patricio Dominguez, Madrid, Spain
The Codex Leicester, written between 1506 and 1510, by the inspiring Renaissance artist, scientist, and thinker, Leonardo da Vinci, includes a page entitled "Of the Moon: No Solid Body is Lighter than Air." Leonardo believed that the Moon has an atmosphere and oceans and because it was covered with so much water, the Moon was a fine reflector of light. Conversely, the Moon was illuminated by sunlight bouncing off Earth's oceans. Leonardo was partially wrong: Moon is a dry world and the Earthshine is mainly due to the white clouds, not to the dark seas. However, Leonardo intuitively understood the phenomenon. The ashen glow is the sunlight bounced two times: first off the earth clouds and then off the lunar surface and it is visible on the night side of the Moon. Each time the light reflects off a surface, it gets dimmer because some of the light is absorbed by the reflecting surface. This image was taken with an exposure of 2.5 seconds, a second picture taken in the same session at 1/60 of second shows a similar level of illumination on the day side of the moon. Ashen glow is about 150 times dimmer than the crescent light side.
Patricio Dominguez
Technical Details
March 29th 2009 19:11:43 UT. William Optics FLT 110 f/7 on Celestron CGE mount, Canon Eos 20D. ISO 100 2.5s
Yesterday's LPOD: Saturnshine
Tomorrow's LPOD: Swirlette
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