NASA’s Curiosity Mars rover recorded this sequence of views of the sun setting at the close of the mission’s 956th Martian day – that’s 15 April, 2015 to us – from Gale Crater.
The four images shown in sequence here were taken over a span of 6 minutes, 51 seconds.
This was the first sunset observed in colour 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 colour very similarly to what human eyes see, although it is actually a little less sensitive to blue than people are.
While it may be the Red Planet, its sunsets are blue because the planet’s atmospheric dust has fine particles that permit blue light to penetrate more efficiently than longer-wavelength colours.
That causes the blue colours 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 colours. The effect is most pronounced near sunset, when light from the Sun passes through a longer path in the atmosphere than it does at mid-day.
For more information about Curiosity, visit NASA’s mission site.