EMBARGOED for
There is no reason to suspect these Martian structures were dug by worms, but
they do resemble wormholes -- or the termite tunnels you might discover around
the foundation of your home.
The features are actually scarps near the south pole of Mars formed by erosion
and sublimation, when ice turns directly to vapor, skipping the liquid phase.
Here's what's going on:
The northern polar cap of Mars contains abundant frozen water ice. Only recently have scientists determined that the same appears to be true in the south. Hiding the frozen southern water, however, is a vast expanse of frozen carbon dioxide, commonly known as dry ice.
The dry ice sublimates at lower temperatures than water ice, and it is doing so right now during summer in the red planet's southern hemisphere. The process can expose the permanent layer of water ice below, generating "Swiss cheese" features in addition to these curved shapes.
You won't be able to see the "wormholes" with a
backyard telescope, but a good-sized amateur eyepiece can reveal the whitish
polar cap right now, as Mars
nears its closest approach to Earth in
nearly 60,000 years. But look soon -- the polar cap is shrinking by the day.
The image, released by NASA last week, covers area just less than a mile (1.5
kilometers) wide near 86.3°S, 51.2°W.
-- Robert
Roy Britt
Credit: NASA/JPL/Malin Space Science Systems
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