Why are sunsets on Mars blue?

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Why are martian sunsets blue? Because the Red Planet’s atmosphere “scatters red“:

Martian dust is exactly the right size to absorb the blue wavelengths of light and scatter red wavelengths all over the sky. That’s why if you are standing on Mars and look away from the setting sun, most of the sky is rosy, pink, and various shades of red. But now look straight at the setting sun. On Mars, the beams of light streaming toward you, having lost their red waves, show the wavelengths that haven’t scattered off. That remaining light is predominantly blue. So when you look straight at the sun on Mars, you see a haze of blue. Look away from the sun, and the light is red. It’s exactly the opposite on Earth.

The photo is via the Mars Exploration Rover Spirit which captured this stunning view as the sun sank below the rim of the Gusev crater. The filter combination used to take this image allows false colour images to be generated that are similar to what the human eye would see, but with the colours slightly exaggerated. Because Mars is farther from the Sun than Earth is, the Sun appears only about two-thirds the size that it appears in a sunset seen from Earth.

Peter Schorsch is the President of Extensive Enterprises and is the publisher of some of Florida’s most influential new media websites, including SaintPetersBlog.com, FloridaPolitics.com, ContextFlorida.com, and Sunburn, the morning read of what’s hot in Florida politics. SaintPetersBlog has for three years running been ranked by the Washington Post as the best state-based blog in Florida. In addition to his publishing efforts, Peter is a political consultant to several of the state’s largest governmental affairs and public relations firms. Peter lives in St. Petersburg with his wife, Michelle, and their daughter, Ella.