Mars is often referred to as the Red Planet, but pictures from one of NASA’s orbiters showed what appeared to be a striking blue sand dune.
The images were captured by the Mars Renaissance Orbiter, using the HiRISE camera, described on its website as “the most powerful camera ever sent to another planet.”
But the dune isn’t actually blue, it’s gray. After an extensive editing process, colors and lines pop out.
Orbiters, unlike rovers, do not touch the ground, but instead monitor the planet from just outside its atmosphere.
Without the camera, the human eye would see a gray slate and not much else. The camera captures a lot more detail, but even that device can’t see everything because of all the dust on the planet.
So three separate images are taken of the area and colors are individually adjusted to red, blue and green using infrared technology, said Alfred McEwen, director of the Planetary Image Research Laboratory at the University of Arizona.
After booting the contrast up, the dune appears turquoise blue because it “is made of finer material and/or has a different composition than the surrounding,” according to a recent NASA press release.
“Then we combine the colors because the images have a very low contrast,” McEwen told CNN.
The dune was found on the Lyot Crater, where most of the other dunes are barchan, or crescent-shaped. They take this shape because of their position facing the wind. It is unclear why the “blue” dune is more abstract.