Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 July 14 
Posted on 07/14/2004 5:00:52 AM PDT by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 July 14
Explanation: What's the best way to the city center? What looks like a street map of some city on Earth is actually a series of naturally-formed fragmented polar polygons on Mars. The existence of polar polygons on Mars is particularly interesting as they may indicate regions where water ice lies within a few meters of the surface. Similar looking polygons are commonly found in the arctic and Antarctic of Earth, where they typically form from a repetitive cycle of freezing and thawing. The above image spans a distance of about 3 kilometers and was taken recently by the orbiting Mars Global Surveyor.
| Clouds Roll in for Martian Winter Using its left navigation camera, the Mars Exploration Rover Opportunity sought to capture some clouds on its 153rd sol on Mars (June 28, 2004). The presence of morning clouds in the area of Endurance Crater was established by spacecraft orbiting Mars. Mars has three kinds of clouds: dust clouds low in the atmosphere; water clouds near the surface up to heights of 20 kilometers (about 12 miles); and carbon dioxide clouds at very high altitudes. Just as on Earth, clouds, especially water clouds, are good tracers of the weather. Based on orbital data, more clouds are expected during the martian winter. As this change occurs, the rover's cameras and miniature thermal emission spectrometer will track other changes that occur as the clouds accumulate. The rovers provide a unique opportunity to examine the lower portion of Mars' atmosphere. The lower atmosphere is difficult to characterize from orbit, but it is critical because that is where the atmosphere interacts with the surface. Since the rovers landed, the science team has been using the rover's miniature thermal emission spectrometer instrument to see the weather at this bottom layer. Image credit: NASA/JPL |
| Browse Image (31 kB) | Large (118 kB) |
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Thank You.
Looks like permafrost lands to me. Same as the land behind my house.
Thanks for the ping
& for posting the thread
Thanks as always for the great thread (and pictures). Have a good evening! :o)
Thanks for posting. I don't need to be on the ping list, I check for the APOD every day. I just wanted you to know that it was appreciated.
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