NASA's Curiosity rover photographed a cloudy sunset on the planet Mars on March 19. The image consists of 21 individual images, stitched and corrected Colour, so that the scene appears as the human eye would see it.
As described in the NASA post, in their Mars sky were observed "bursts of clouds filled with ice crystals that scatter light from the setting sun, some of which shimmer in color."
According to NASA, clouds are rare in Mars' thin atmosphere, but they usually form at the equator during the coldest time of year. Scientists noticed that last year (before two years according to Earth time) there were clouds starting to form earlier than expected, so this year they were ready to observe them.
The images are not only impressive, but gave new information to NASA's Curiosity team. The first clouds are at higher altitudes than most Martian clouds, which typically hover around 60 kilometers above the surface of the planet and are composed of water ice. Higher-altitude clouds are likely made of frozen carbon dioxide, or dry ice, according to NASA.
NASA's poetic description is also impressive: Shortly after sunset, ice crystals caught the faded light, making them appear to glow in the dark sky. These twilight clouds, also known as "noctilucent" (Latin for "night flashes"), grow larger and brighter as they fill with crystals, and then darken when the Sun's position in the sky falls below an altitude.
Mark Lemmon, a scientist at the Space Science Institute in Boulder, Colorado, said in a NASA publication that these colors come from cloud particles of almost identical size. "This usually happens because as soon as the clouds form, they all grow at the same rate."
Lemmon said the colors that appear in these clouds are red, green, blue and purple. "It's very nice to see something shining on Mars, with a lot of color."
