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.

2003 December 30
See Explanation.  Clicking on the picture will download
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A Dust Devil Crater on Mars
Credit: Malin Space Science Systems, MGS, JPL, NASA

Explanation: What caused the streaks in this Martian crater? Since the above image shows streaks occurring both inside and outside the crater, they were surely created after the crater-causing impact. Newly formed trails like these presented researchers with a tantalizing martian mystery but have now been identified as likely the work of miniature wind vortices known to occur on the red planet - martian dust devils. Another example of wind processes on an active Mars, dust devils had been detected passing near the Viking and Mars Pathfinder landers. Such spinning columns of rising air heated by the warm surface are common in dry and desert areas on planet Earth. Typically lasting only a few minutes, they becoming visible as they pick up loose dust. On Mars, dust devils can be up to 8 kilometers high and leave dark trails as they disturb the bright, reflective surface dust.

Tomorrow's picture: A Year of Resolving Cosmology

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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