NASA Mars rover sends back photos of shimmering, otherworldly clouds

Mars doesn’t have too many cloudy days, so this new set of images from a NASA-operated rover is a full-on treat.

The Curiosity rover has been gathering data on the Red Planet since it touched down in Aug. 2016. And now, while many space watchers’ eyes are turned toward the Perseverance rover and Ingenuity helicopter that both arrived in February, Curiosity is here to remind us that it’s still putting in plenty of work, too.

So. Back to clouds. They’re not as common on Mars as they are on Earth because the Mars atmosphere is thin and dry, and the clouds that we all see here on Earth are basically just floating water vapor. They do happen on Mars, but it’s usually near the planet’s equator and only during the winter when Mars’ orbit takes it as far from the sun as it ever gets. 

But about two years ago, NASA’s Jet Propulsion Laboratory writes, researchers took note of the sparse cloud cover popping up earlier than expected. So now, in 2021, the U.S. space agency was ready to document those early clouds when they formed in the Martian skies back in January.

The thin and wispy trails of vapor strike quite an image against the dreary backdrop of grey skies — it’s not overcast, this is just what a Mars sunset looks like — and nondescript terrain that is uniformly rusty in color.

The cloud cover’s faint glow is a product of the sun’s rays hitting them. Mars is about 60 million miles more distant from the sun than Earth, so our solar system’s central star doesn’t reach the planet with the same intensity. But it’s still shining bright enough to suffuse these clouds with an otherworldly glow.

As NASA’s post notes, the research unfolding here is about more than just sending pretty pictures back to Earth. Observing these clouds is helping scientists better understand why they’re even forming so early in the first place.

“In fact, Curiosity’s team has already made one new discovery: The early-arrival clouds are actually at higher altitudes than is typical,” the post reads. “Most Martian clouds hover no more than about 37 miles (60 kilometers) in the sky and are composed of water ice. But the clouds Curiosity has imaged are at a higher altitude, where it’s very cold, indicating that they are likely made of frozen carbon dioxide, or dry ice.”

A few weeks later, in March, the Curiosity again captured some sweet views of the Martian skies. The stitched-together photo below captures so-called “mother of pearl” clouds, whose iridescent colors are a product of the way these clouds form.

“If you see a cloud with a shimmery pastel set of colors in it, that’s because the cloud particles are all nearly identical in size,” Mark Lemmon, an atmospheric scientist with the Space Science Institute in Colorado, said in NASA’s post. “That’s usually happening just after the clouds have formed and have all grown at the same rate.”

The colors wouldn’t be as clear to the eye if we were sitting there next to Curiosity, so this kind of view is a rare treat.