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NASA’s Curiosity rover has spent 1,890 Martian days on the red planet since it landed there early in the morning of August 6, 2012. That’s 1,890 sunsets and 1,890 sunrises as the robot does its science, puttering around Gale Crater looking for interesting rocks to study.
Usually, we don’t get to see all those sunsets and sunrises, since Curiosity and its cameras are busily focused on the terrain around it. But every so often, the robot turns its eyes to the skies, and when it does, Damia Bouic, who processes photographs from Curiosity and other Mars rovers, is waiting.
“I just like sunset pictures, the way the landscape is transformed into a game of shadows and how the light and colors are scattering into the atmosphere,” Bouic wrote in an email to Newsweek.
That blueish tinge to the scene is not artistic license—despite the planet’s red reputation, Bouic says, a sunset on Mars would look blue, even to our eyes. The sun itself doesn’t change, of course, it’s just a matter of looking different through a different atmosphere.
“The colors come from the fact that the very fine dust is the right size so that blue light penetrates the atmosphere slightly more efficiently,” Mark Lemmon, an atmospheric scientist at Texas A&M University, College Station, and one of Curiosity’s operators, told NASA in 2015 about a similar image. “When the blue light scatters off the dust, it stays closer to the direction of the sun than light of other colors does. The rest of the sky is yellow to orange, as yellow and red light scatter all over the sky instead of being absorbed or staying close to the sun.”
If you were on Mars, though, you would have to wait a bit longer to catch a sunset than you do here on Earth: The planet takes 24 hours and 37 minutes to spin once on its axis.
The rover was originally designed to spend about two years on Mars, but since then, Curiosity’s duties have been extended twice, since it is holding up well to the stresses of the environment. (Even that pales next to the planet’s hardest-working rover, Opportunity, which NASA planned to use for 90 days and has instead lasted 13 years.)
Lately, Curiosity has been looking for dust devils and clouds, as well as studying a fan-like deposit and what scientists think may be an impact crater.