CAPE CANAVERAL, Florida - For the first time, NASA's Curiosity Mars rover has sent back to Earth color images of a blue sunset on Mars.
According to NASA, dust in the Martian atmosphere has fine particles that permit blue light to penetrate the atmosphere more efficiently than longer-wavelength colors. That causes the blue colors in the mixed light coming from the sun to stay closer to sun's part of the sky, compared to the wider scattering of yellow and red colors - similar to the phenomena caused by ash from forest fires and volcano eruptions that create the occasional appearance of Blue Moons on Earth. The effect is most pronounced just before the Martian sunset, when light from the sun passes through a longer path in the atmosphere than it does at mid-day.
This was the first Martian sunset observed in color by Curiosity. The images come from the left-eye camera of the rover's Mast Camera (Mastcam). The color has been calibrated and white-balanced to remove camera artifacts. Mastcam sees color very similarly to what human eyes see, although it is actually a little less sensitive to blue than people are.
Image Credit: NASA/JPL-Caltech/MSSS/Texas A&M Univ.