Blue sunset on Mars

Why is the sunset on Mars blue?
If we know well the flamboyant sunsets, which can be admired at every corner of the planet, the sunset on Mars, it has something unusual: it is blue.

Credit: NASA / JPL-Caltech / MSSS / Texas A & M Univ.

Although new machines appear in the landscape of the space conquest, the ancients continue to send us dreams. Among them, Curiosity, the rover that roams the surface of the planet Mars since 2012.

In charge of the issue of the emergence of life on the red planet, the probe nevertheless had the time to immortalize his trip. And among the photos she transmitted to Earth, there is this amazing sunset, photographed from the center of the crater Gale.

This shot, which is the first color photo made by the rover, is once again emerging on social networks since the landing of the InSight probe on November 26th. And what is the surprise to rediscover that the sunset on Mars is actually not red but … blue.
An overloaded atmosphere

Unlike its name, which primarily represents the color of its soil, the red planet does not undergo glowing sunsets as can be seen on Earth. This shot was taken by the left camera of the Mastcam of the rover, which is a little less sensitive to the blue color than the human being. It is therefore necessary to imagine it even more blue (even purple) than it appears on the photo.

But what is the reason for this strange color? The answer lies in the Martian atmosphere, very different from that of the Earth. Composed of fine particles, it lets the blue light pass more easily than other colors, which disperses faster because of its longer wavelengths.

And this effect is accentuated more at sunset when the light of the star follows a path in the atmosphere longer than at midday. The only color that reaches the surface of the planet is blue.

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