Weird dunes on Mars
This image, captured in January 2020 and released just last week, was taken by NASA’s Mars Reconnaissance Orbiter, and it shows two different sand dunes on Mars: barchan and linear dunes. NASA explains:
The small dots are called barchan dunes, and from their shape we can tell that they are upwind. The downwind dunes are long and linear. These two types of dune each show the wind direction in different ways: the barchans have a steep slope and crescent-shaped “horns” that point downwind, while the linear dunes are stretched out along the primary wind direction. Linear dunes, however, typically indicate at least two different prevailing winds, which stretch out the sand along their average direction.
Interestingly, the same phenomena can be found on Earth, including in Brazil and Saudi Arabia.
