The Dotted Dunes of Mars
Explanation:
What causes the black dots on dunes on Mars?
As spring dawns on the Northern Hemisphere of
Mars, dunes of sand near the poles being to defrost.
Thinner regions of ice typically thaw first
revealing sand whose darkness soaks in sunlight and accelerates the thaw.
By summer, the
spots will have expanded to encompass the entire
dunes that will then be completely thawed and dark.
The
carbon dioxide and water ice actually
sublimes
in the
thin atmosphere directly to gas.
Taken in mid-July, the
above image shows a field of
spotted polar dunes spanning about 3 kilometers near the Martian North Pole.
Meanwhile, in the
Southern Hemisphere of Mars, the Earth-sent
robot Martian rovers will
try to survive through Martian winter, which peaks in mid-September.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
