Less than three years after it landed on Mars, NASA’s Curiosity rover has captured the first color images of sunset on the red planet. The event was recorded at the close of the mission’s 956th Martian day, or sol, on April 15 from the rover's location in Gale Crater.
The set of four images, taken over a span of 6 minutes and 51 seconds, were captured using the left-eye camera of the rover's Mast Camera (Mastcam), which has the ability to see colors in a fashion similar to that of the human eye, NASA said, adding that the imaging was done between dust storms.
“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,” Curiosity team member Mark Lemmon of Texas A&M University said in a statement. “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.”
According to NASA, the observed color effect is more prominent near sunset, when light from the sun passes through a longer path in the atmosphere than it does at the middle of the day.
The images were sent to Earth from the Mastcam in black and white. However, they contained coded information, which can reveal color when decoded, the Washington Post reported.
“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,” NASA said in a statement.