In today's image, we see an are on Mars which once contained liquid water. Mars is no longer able to have water in liquid form because of its low atmospheric pressure, but there is strong evidence that liquid water did exist on the surface billions of years ago.

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This Podcast is an authorized New Media Mirror Site for APOD. You can access the image and website directly at: Astronomy Picture of the Day. You can use the archive link below the image to select the photo corresponding to the date of this podcast.

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