As part of its ongoing study of clouds on Mars, NASA’s Curiosity rover recently captured a Stunning image of a Martian sunset. As the sun sinks below the horizon, its light is converted into sunbeams that can be seen in bands across the sky.

Technically known as crepuscular rays, this is the first time the phenomenon has been imaged in such detail on Mars. And by studying the way lightning shines through clouds, scientists can learn more about the Martian atmosphere and weather system.

Although the atmosphere of Mars is extremely thin, only 1 percent as dense as Earth’s atmosphere, it is still active and changing. The planet experiences strong winds of up to 60 miles per hour, which can pick up the fine dust particles that cover much of the planet’s surface and turn them into global dust storms. With low atmospheric pressure and considerable variation in temperatures between day and night, dynamic events such as dust eddies are regularly observed.

Also due to the thin atmosphere, there are only occasional clouds in the Martian sky. With only small amounts of water vapor present in the atmosphere, the presence of clouds varies throughout the seasons. However, the clouds that are visible there are not like clouds on Earth, as they are made up of liquid water. On Mars, low pressure means that clouds are formed from water ice or carbon dioxide (dry ice).

The new images from Curiosity show clouds at high altitudes, suggesting they are composed of carbon dioxide rather than water ice. Another recently captured image by Curiosity shows another important cloud phenomenon called iridescence. The different colors seen within the cloud can reveal information about the particles that make it up.

“Where we see iridescence, it means that the particle size of one cloud is identical to its neighbors in every part of the cloud,” said Mark Lemmon, an atmospheric scientist at the Institute for Space Sciences in Boulder, Colorado, in a statement. statements. “By looking at the color transitions, we see that the size of the particles changes in the cloud. That tells us how the cloud is evolving and how its particles are changing size over time.”

The two images were stitched together from 28 individual images each. They were taken by Curiosity’s Mastcam instrument, which, unlike many previous cloud observations made with the rover’s black-and-white navigation cameras, can capture color images. Curiosity has been conducting its cloud survey since January and will continue for a few more weeks.

Curiosity has previously captured other amazing views of Martian weather phenomena, such as the blue sunset it captured in 2015. The color seen there is also due to dust in the atmosphere, following a dust storm that had left dust suspended. in the atmosphere. This suspended dust scatters different colors of light in different amounts and scatters the light in a particular direction. That results in more of the red light being filtered out, so what’s left is the blue color seen in the Martian sky.