Air Glow, Milky Way and the Great Lake Alqueva

By: Miguel Claro


Reserva, Portugal

2013 June 15


A Notable Photo of the 2014 International Earth & Sky Photo Contest.
From the photographer: "This serene view is captured on the great lake Alqueva, near the “Ermida de São Pedro” in Mourão, one of the regions belonging to the Dark Sky Alqueva Reserve, we find several scientifically interesting things. In the center of the picture we can see the natural colors of the most central region of the Milky Way, located near the Scorpius and Sagittarius constellations, where is it possible to recognize many deep sky objects like the Lagoon Nebula (M8) and the Trifid Nebula (M20). Also a strong presence of Air Glow (Atmospheric Chemiluminescence) is visible with yellow light, by emissions from sodium atoms in a layer at 92 km. Above it, we could see the green light from oxygen atoms in a layer 90-100 km high. This emission layer is clearly visible from earth orbit.
Reflected in the peaceful lake and due to the polarization effect of water, we could clearly see the entire constellation of Scorpius with the real color of each star naturally saturated, due to this polarization and blurred effect, caused by the slowly movement of water during the long exposure. The orange color of the Red Supergiant Antares could be easily distinguished from the blue color of the Subgiant star, Shaula, in the end of the Scorpion's tail.
Canon 60Da – ISO 1600; 35mm lens at f/2; Exp. 15 secs. Mosaic of 23 images."
Miguel Claro -

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