Most clouds on the Red planet hover at about 37 miles (60 kilometres) or lower in the sky, and are composed of water ice. The latest capture by Curiosity shows the clouds at a higher altitude, where it is very cold.
This picture was not shot from the Grand Canyon in the U.S.
In fact, this image was not even photographed on Earth. This is a picture of
Mont Mercou, Joa cliff on Mars. The contrast of grey clouds over the brown
mountain was shot by NASA’s Curiosity rover on March 19, 2021 - - the day it
completed 3,063 Martian days, (one day in Mars is called sol).
The picture is a collection of 21 separate images stitched
together and colour corrected so that the location appears as how it would to a
human eye. The rover has been studying this cliff to better understand the Red
planet.
While spotting clouds on Mars is rare, this capture by the
rover is an even rarer phenomenon. That’s because, to the extent we know about
the fourth planet, clouds typically appear during the coldest time of the year
near Mars’ equator when planet is farthest from the Sun. Two Earth years ago
(one full Mars year), scientists at NASA noticed clouds forming over the rover
earlier than expected.
That’s when they decided to look deeper into this phenomenon
early on. So, they started to track the “early” clouds in late January and
spotted “wispy puffs” filled with ice crystals that scattered light from the
setting Sun, some shimmered with colours. The Curiosity team analysing the
clouds were more interested in how these ‘puffs’ are formed than in their
spectacular displays.
Initial discovery and clues to next
When it made its first discovery of clouds on Mars, the team
noted that, “The early-arrival clouds are actually at higher altitudes than is
typical.” Most clouds on the Red planet hover at about 37 miles (60 kilometres)
or lower in the sky, and are composed of water ice. The latest capture by
Curiosity shows the clouds at a higher altitude, where it is very cold. This
translates to a higher likelihood of clouds formed by frozen carbon dioxide or
dry ice, NASA said in a blog post.
“I always marvel at the colours that show up: reds and
greens and blues and purples,” Mark Lemmon, atmospheric scientist at Space
Science Institute in the U.S., told NASA. “It’s really cool to see something
shining with lots of colour on Mars.”
The findings are not final yet as scientists will need to do
more analysis to know for sure which of the recent images photographed by
Curiosity has water-ice clouds and which one has dry-ice ones. One of the clues
scientists use to determine the altitude of the clouds is by looking at
twilight clouds, also known as “noctilucent”. During sunset, the ice crystals
in the cloud catches the fading light, which makes them glow against the
darkening sky. They gradually darken as the Sun’s position in the sky drops
below their altitude. This will help scientists calculate the position of the
clouds in the sky.
Discoveries like this by the Curiosity rover helps
scientists to better understand Earth’s neighbour, its topography and climactic
conditions.