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.
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.