Saturday, October 31, 2015

A Blue Blood Moon

A Blue Blood Moon:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 October 3


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: This sharp telescopic snapshot caught late September's Harvest Moon completely immersed in Earth's dark umbral shadow, at the beginning of a total lunar eclipse. It was the final eclipse in a tetrad, a string of four consecutive total lunar eclipses. A dark apparition of the Full Moon near perigee, this total eclipse's color was a deep blood red, the lunar surface reflecting light within Earth's shadow filtered through the lower atmosphere. Seen from a lunar perspective, the reddened light comes from all the sunsets and sunrises around the edges of a silhouetted Earth. But close to the shadow's edge, the limb of the eclipsed Moon shows a distinct blue hue. The blue eclipsed moonlight is still filtered through Earth's atmosphere though, originating as rays of sunlight pass through layers high in the upper stratosphere, colored by ozone that scatters red light and transmits blue.

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