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.
2002 September 3 
Posted on 09/02/2002 10:32:34 PM 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.
2002 September 3
Explanation: Does the surface of Mars change? When inspecting yearly images of the Martian surface taken by the robot spacecraft Mars Global Surveyor currently orbiting Mars, sometimes new dark trails are visible. Although originally a mystery, the culprit is now usually known to be a dust devil, a huge swirling gas-cloud with similarities to a terrestrial tornado. Pictured above, a recent image has not only captured a new dark trail but the actual dust devil itself climbing a crater wall. Dust devils are created when Martian air is heated by a warm surface and begins to spin as it rises. Dust devils can stretch 8 kilometers high but usually last only a few minutes.
Mars' carbon dioxide atmosphere is only 1% as dense as Earth's at sea level.
A 100 mph wind would feel like a light breeze, but would be blowing dust and sand.
Be sure to click on the "Martian air" link in the above article and read about the Kitty Hawk (!) project.
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On my way home that day, I saw the scattered pages from that notebook strewn through a housing tract 1/2 mile away.
We lived in Mountain Home AFB, Idaho when I was a kid (Air Force Brat!). That's the desert part of Idaho (southwestern Idaho). We saw dust-devils all the time there. What I remember that was such a strange thing was living across the street from the Base Golf driving range. They had water sprinklers going all the time and it was lush green. We could walk down the street about 2 blocks or so and there was a barricade at the dead end street. Beyond the barricade? Nothing but sagebrush, sand scorpion dusty desert. It was a strange thing to see such a stark contrast on base/off base.
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