Lunar eclipses are supposed to be red, yet when the Moon passed through Earth's amber shadow on April 15th, many observers witnessed a softly-glowing band of turquoise blue. Robert and Elisabeth Slobins send this picture of the phenomenon from Fort Myers, Florida:
The source of the turquoise is ozone. Prof. Richard Keen, an atmospheric scientist from the University of Colorado explains: "During a lunar eclipse, most of the light illuminating the Moon passes through the stratosphere, and is reddened by scattering. However, light passing through the upper stratosphere penetrates the ozone layer, which absorbs red light and actually makes the passing light ray bluer!" This can be seen, he says, as a turquoise fringe around the red.
For years, Keen has been using lunar eclipses to probe the transparency of the stratosphere. When the stratosphere is clogged with volcanic ash and other aerosols, lunar eclipses tend to be dark red.
The bright orange color of the April 15th eclipse, along with the ready visibility of the turquoise fringe, suggests that the stratosphere is clear. This is a key finding for climate change models.
To see the effects of ozone on the eclipse, you have to be looking at just the right moment.
Readers are invited to browse the gallery for more examples: Realtime Eclipse Photo Gallery. www.spaceweather.com
For years, Keen has been using lunar eclipses to probe the transparency of the stratosphere. When the stratosphere is clogged with volcanic ash and other aerosols, lunar eclipses tend to be dark red.
The bright orange color of the April 15th eclipse, along with the ready visibility of the turquoise fringe, suggests that the stratosphere is clear. This is a key finding for climate change models.
To see the effects of ozone on the eclipse, you have to be looking at just the right moment.
Readers are invited to browse the gallery for more examples: Realtime Eclipse Photo Gallery. www.spaceweather.com
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