A Blue Blood Moon

Astronomy Picture of the Day · 2015-10-03 · NASA (public domain)

A Blue Blood Moon — APOD for 2015-10-03

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.

Astronomy Picture of the Day for 2015-10-03 — image & explanation courtesy of NASA (public domain), mirrored at Tukuk-OS for reading and search convenience.