A Mars rover has watched some spectacular sunsets recently, with sightings of iridescent, featherlike clouds and sun rays poking through the blanketed sky.
The NASA explorer isn’t taking pictures for the ‘Gram to give all its rover pals FOMO, but to study clouds at twilight, building on research that began two years ago when it observed night-shining clouds.
The new images are a reminder that even a glance up at the sky from the surface of Mars is an alien experience, showcasing phenomena that rarely or don’t exist in our world. Last year a United Arab Emirates Space Agency probe orbiting Mars, known as Hope, captured a gigantic green wormlike aurora above the planet that stretches thousands of miles from the sun-facing side to the back. And researchers affiliated with the European Space Agency have discovered a California-size cloud that shows up every spring in southern Mars over a dead volcano.
Curiosity is adding to scientists’ growing bank of knowledge about the Martian sky. It captured a set of feathery rainbow-like clouds on Jan. 27. When lit by the sun, these types of clouds appear as iridescent as mother of pearl jewelry, displaying a kaleidoscope of colors. Though rainbow clouds can occur over Earth when they’re thin and have lots of uniform water droplets or ice crystals, they’re extremely rare.
“Where we see iridescence, it means a cloud’s particle sizes are identical to their neighbors in each part of the cloud,” Mark Lemmon, an atmospheric scientist with the Space Science Institute in Colorado, said in a statement. “By looking at color transitions, we’re seeing particle size changing across the cloud. That tells us about the way the cloud is evolving and how its particles are changing size over time.”
Curiosity’s photoshoot on Feb. 2 also showed sun rays pouring through Martian clouds. The rover has captured these beams on the Red Planet before, but never this clearly.
Credit: NASA / JPL-Caltech / MSSS / Texas A&M Univ.
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Most clouds hovering over Mars are no more than 37 miles above ground and made of water ice. But these recent puffs, likely composed of carbon dioxide, are more like dry ice. They’re much higher up, where the temperatures are even more frigid.
The cloud survey, which will wrap up in mid-March, uses the rover’s color Mastcam. Scientists stitched together the panoramic images of the iridescent cloud and sun rays from over two dozen separate pictures sent back to Earth. They plan to use the observations to glean more information about Mars’ atmosphere, temperatures, and weather.
