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The Earth's shadow sweeps westward and downwards to mask a volcanic twilight glow. Imaged in Kansas Aug '08 by Doug Zubenel. Image ©Doug Zubenel.

We usually look for the Earth's shadow in the east after sunset. However, Doug points out that here it appears in the west. A layer of volcanic ash high in the atmosphere over the USA and now, Aug 30, over Europe also scattered sunlight and the shadow of the earth progressivly snuffed out the glow. The shadow rises in the east, sweeps quickly across the zenith and then descends to the west. Doug's last picture (4) was taken when the sun was 6.2° below the horizon and some trigonometry shows that the ash layer was at an altitude of ~50,000 ft in the stratosphere.