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The Carnigou Massif in the Pyrenees from 165 miles away imaged October 26, '08 by Alain Origne of Laboratoire Astrophysique Marseille (more images). Image ©Alain Origne, shown with permission.

What is remarkable about these images is less the mock-mirage green flash (see the animation) but that the top of a mountain in the distant Pyrenees can be seen silhouetted against the solar disk.   

Alain was on a 1000 ft hill near Marseilles, France and looked out across the Mediterranean. The silhouette is of 8900 ft Mt Roc Negro, part of the Canigou Massif 165 miles distant.

There is no direct line of sight to the mountain because of the Earth's curvature. The view is only possible because light is refracted around the earth by passage between the dense lower and less dense upper regions of the atmosphere. This refraction raises the sun by ~0.5° when it is at the horizon and it can raise very distant terrestrial objects also.

This is not a chance observation, Alain Origne has made a systematic study of the phenomenon and predicts when it will occur. He would like to hear of other long distance sightings.

See next OpticsPOD for lunar views of distant mountains.
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