What do you think of this fact?
Mars is called the red planet, and during the day that fits: its sky looks reddish to brownish. But once the Sun goes down, it flips the colors around.
A sunset in blue
On April 15, 2015, NASA’s Curiosity rover recorded a sunset in color from Gale Crater, over a span of seven minutes. The result: around the setting Sun, the sky glows bluish, a cool shimmer you never see on Earth.
Curiosity was not a one-off. According to IFLScience, the rovers Spirit and Opportunity also captured blue sunsets on Mars.
Blame the dust
On Earth, evenings turn red because molecules in the air scatter mostly blue light in all directions. When the Sun is low, its light has to travel a long way through the atmosphere. The blue gets lost on the way, and the red reaches you.
The air on Mars is extremely thin. According to IFLScience, the pressure is only about 1 percent of Earth’s. Instead, lots of fine dust floats around. And that dust behaves differently from our air: NASA says it lets blue light pass through the atmosphere more efficiently than red light. So the red gets scattered away, and the lower the Sun sinks, the more a blue glow stays near it.
During the day, that same dust is what makes the Martian sky look reddish. One planet, two color schemes, depending on the time of day.
Bonus fact: According to NASA, dust in the Martian atmosphere is especially common during the Martian spring, which is when the blue effect shows up best.
On Mars, red only works the day shift.