Lunar alpenglow and Orion
Jeff Dai wrote from Tibet about this image, which he captured on October 22, 2015. He said:
Winter is coming, and it’s time to enjoy the famous constellation Orion. In this 5-second exposure, the setting moon casts lunar alpenglow on the sacred Chana Dorje peak at Yading National Nature Reserve, Sichuan province of China. In the background sky, the three Belt stars of Orion can be seen lined up almost vertically above the pyramid peak. The Horsehead Nebula is also visible near the Belt stars, and to the right is the great Orion Nebula, also known as M42. The red-glowing circular structure surrounding Orion is Barnard’s Loop. The bright red star Betelgeuse and blue Rigel appears on the both sides of the image.
Canon 6D. Lens: EF 85mm f/1.8 USM
Single exposure at 85mm, ISO 6400, f2.0, 5 seconds
Thank you, Jeff!
By the way, the meaning of the word alpenglow has been shifting in recent years. We asked a true expert, Les Cowley of the website Atmospheric Optics, and he told EarthSky:
It’s a matter of definition. Purists would define an alpenglow as the rosy-red light on easterly mountains after the sun has set. The light comes from the sky’s bright twilight arc in the west.
However, the term also tends to be used nowadays for the sunlight on mountains when the sun has already set at ground level but is still shining at higher altitudes.
Here, Jeff is using the term alpenglow not just for lingering sunlight … but for a glow cast on easterly mountains as the moon is setting.
Bottom line: Constellation Orion, and all that surrounds it in the sky, plus light from the setting moon on the sacred Chana Dorje peak in Tibet. Photographer Jeff Dai is calling this light lunar alpenglow.