The NASA Curiosity rover has captured new images of ‘shining clouds’ on Mars, which formed earlier in the year and higher than expected. Scientists will now study the images to learn more about the Red Planet.
According to NASA Jet Propulsion Laboratory, cloudy days are rare in the thin, dry atmosphere of Mars. Clouds are typically found at the planet’s equator in the coldest time of year, when Mars is the farthest from the Sun. But one full Martian year ago (two Earth years) scientists noticed clouds forming over NASA’s Curiosity rover in late January – earlier than expected.
This year the scientists were prepared to document these clouds and captured images of wispy puffs filled with ice crystals that scattered light from the setting Sun, some of them shimmering with color.
The Curiosity team will now analyze these images to learn more about the atmosphere on Mars. The team has already discovered that the early-arrival clouds are at higher altitudes than is typical.
Most Martian clouds hover no more than about 37 miles (60km) 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. Scientists look for subtle clues to establish a cloud’s altitude, and it will take more analysis to say for sure which of Curiosity’s recent images show water-ice clouds and which show dry-ice ones.
The images were taken using Curiosity’s black-and-white navigation cameras and its color Mast Camera (Mastcam). Viewed just after sunset, the clouds’ ice crystals catch the fading light, causing them to appear to glow against the darkening sky. These twilight clouds, also known as noctilucent clouds, grow brighter as they fill with crystals, then darken after the Sun’s position in the sky drops below their altitude. This is just one clue scientists use to determine how high they are.
Curiosity also captured iridescent, or ‘mother of pearl’ clouds. Mark Lemmon, an atmospheric scientist with the Space Science Institute in Boulder, Colorado, said, “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. That’s usually happening just after the clouds have formed and have all grown at the same rate.”
For more about Curiosity, visit: https://mars.nasa.gov/msl/