as small as a world and as large as alone

12:54am January 27, 2015

spaceplasma:

Sunset Watched by Opportunity

Mars is often described as the “Red Planet” due to its reddish appearance, however, the combination of dust particles and atmospheric conditions on Mars make for some unusual sunset colors; both the sun’s disk and the sky surrounding the sun appear blue at sunset. 

Mars has a thin atmosphere that is dominated by dust; the reddish color of the sky is caused by the fine red dust (oxidized iron) that is suspended in the Martian atmosphere, the blue glow surrounding the sun is created by light scattered at small angles by the very same dust particles. While the disk of the sun would only appear blue at sunset, when the optical path is longest, or when sunlight passes through a larger amount of dust, e.g.  during a dust storm, the blue glow around the sun should be visible throughout the Martian day.

Credit: NASA/JPL-Caltech/Cornell/Texas A&M

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