Astro-images of the day: Mars South Pole is water ice!

This is exciting: A new study reveals that the South Polar Cap on Mars is water ice, not carbon dioxide ice as previously assumed. In fact, scientists now say that Mars has the second-largest heap of water ice in the whole Solar System, second only to Earth.

This first photo shows the ice cap:

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This close-up shot shows the cap in a photo taken in 2004, when scientists first hypothesized that it could be water ice:

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So if Mars has water ice now, it's even more clear that - in its distant history - it once had open water. Here's a pretty photo of a channel on Mars formed by flowing water:

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Best,
Chris