Explanation:
When does Mars act like a liquid?
Although liquids freeze and evaporate quickly into the
thin atmosphere of Mars, persistent winds may make large
sand dunes appear to flow and even drip like a liquid.
Visible on the
above image right are two flat top mesas in southern Mars, where the
season is changing from Spring to Summer.
A light dome topped hill is also visible on the far left of
the image.
As winds blow from right to left, flowing sand on and around the hills leaves
picturesque streaks.
The dark arc-shaped
droplets of fine sand are called
barchans,
and are the interplanetary cousins of similar Earth-based sand forms.
Barchans can move intact downwind and can even appear to pass through each other.
Over the past few weeks,
winds on southern Mars have been kicking up dust and are
being watched to see if they
escalate into another of Mars' famous planet-scale
sand storms.
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