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Tall boulder rolls down martian hill, lands upright

The shadow cast by the rock in midafternoon sunlight reveals it is about 20 feet (6 meters) tall and about 11.5 feet (3.5 meters) wide.
RELATED TOPICS: SOLAR SYSTEM | MARS
Boulder trail on Mars
The track left by an oblong boulder as it tumbled down a slope on Mars runs from upper left to right center of this image. The boulder came to rest in an upright attitude at the downhill end of the track. The HiRISE camera on NASA's Mars Reconnaissance Orbiter recorded this view on July 3, 2014.
NASA/JPL-Caltech/Univ. of Arizona
A track about one-third of a mile (500 meters) long on Mars shows where an irregularly shaped boulder careened downhill to its current upright position as seen in a July 3, 2014, image from the High Resolution Imaging Science Experiment (HiRISE) camera aboard NASA's Mars Reconnaissance Orbiter.

The shadow cast by the rock in midafternoon sunlight reveals it is about 20 feet (6 meters) tall. In the downward-looking image, the boulder is only about 11.5 feet (3.5 meters) wide. It happened to come to rest with its long dimension vertical. The trail it left on the slope has a pattern that suggests the boulder couldn't roll smoothly or straight due to its shape.
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