Mars, the Red Planet, has a blue sunset! The very fine dust particles in the Martian atmosphere are the right size so that blue light penetrates the atmosphere slightly more efficiently. When this light scatters off the dust, it stays closer to the direction of the sun than the light of other colours. The rest of the sky is yellow to orange, as yellow and red light scatter all over the sky instead of staying close to the sun.
Mars’ atmosphere is very tenuous – its pressure is equivalent to about 1 percent of Earth’s. It is made of carbon dioxide and has a lot of dust. This fine dust tends to scatter red light so that the sky appears reddish, which lets the blue light through. On Earth, it is the other way around. Blue light bounces off air molecules giving our sky its characteristic hue.
At sunset light has a longer distance to travel within the atmosphere, so it scatters more. What is left is the color that we see. On Earth, we have a wider palette of reds, which is actually amplified by ash from volcanoes and dust from fires. On Mars, we get a cool blue hue.
Picture Credit : Google
