August 31, 2018

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Lunar Black Drop?

Originally published June 18, 2009 LPOD-June18-09.jpg
image by Chris Kotsiopoulos, Greece

A most enigmatic phenomenon known as 'black drop effect' is known from when the planet Venus transits in front of the Sun. It is seen as a dark patch appears to connect Venus with the dark sky past the edge of the Sun, sometimes giving Venus a teardrop shape. The leading theory suggests that under exceptional seeing conditions combined with very good optics the effect may not be visible at all. But how does all this relate to this image? Look closely to the front of the plane. A distinct black drop effect is visible where the nose of the aircraft approaches the edge of the Moon. In this case, it is more obvious than the typical Sun - Venus black drop effect. Apparently, the effect can be observed and recorded with any transiting object in front of the Sun or the Moon. But why is this one is so distinct? Perhaps the speed of the passing object is also a factor.

Chris Kotsiopoulos

Technical Details
7/6/2009 1:28. Canon EOS DIGITAL REBEL XTi + Skywatcher ED 80; Shutter Speed 1/160 and Aperture Value 7.5, ISO 100.

Related Links
Chris' webpage

Yesterday's LPOD: Beyond the Cat's Smile

Tomorrow's LPOD: Return To the Moon, Finally


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