Pumpkin Moon Over the Hindu Kush
October 31, 2016
Summary Author: Rob Sheridan
For the past 100 million years, the Indian Tectonic Plate has been pushing approximately north into the Eurasian Plate, progressively obliterating and elevating the remnant bed of the ancient Tethys Sea. The Hindu Kush Mountains of Afghanistan are a constantly growing result. They're also eroding, creating an enormous amount of fine clay soil and dust from what was once the Tethys seabed. During dry spells, mountain winds drive this fine dust into the air, making Afghan dust a constant companion when visiting its dry valleys. Atmospheric dust has a strong scattering and absorbing effect on incident light that increases with the length of the light path and density of dust. This effect is more intense with higher energy, shorter wavelengths (blues and greens), favoring the transmission of the longer wavelength, lower energy red and oranges colors to our eye.
This photo of the full Moon rising over the Hindu Kush in eastern Afghanistan is remarkable for the Moon’s brilliant orange color, like a great pumpkin. It was taken just after sunset on February 3, 2015. Sunlight reflecting off the Moon traversed the Afghan atmosphere before reaching the camera. This lengthy light path favored filtering of all but the longest wavelengths of light. The weather had been dry and blustery, creating a huge amount of airborne dust: Not good for the cameraman's eyes or the camera, but great for the view of the Moon!Photo Details: Camera Maker: NIKON; Camera Model: COOLPIX S9700; Focal Length: 351.0mm (35mm equivalent: 750mm); Digital Zoom: 2.600x; Aperture: ƒ/6.4; Exposure Time: 0.017 s (1/60); ISO equiv: 500.