Two Moons Passing in the Night (Labeled)

Taking advantage of extra solar energy collected during the day, NASA's Spirit rover settled in for an evening of stargazing, photographing the two moons of Mars as they crossed the night sky. "It is incredibly cool to be running an observatory on another planet," said planetary scientist Jim Bell, lead scientist for the panoramic cameras (Pancam) at Cornell University. In this animation, both martian moons, Deimos on the left and Phobos on the right, travel across the night sky in front of the constellation Sagittarius. In this view, Sagittarius resembles an upside-down teapot; Phobos moves toward the handle and Deimos moves toward the lid. Phobos is the brighter object on the right; Deimos is on the left. Each of the stars in Sagittarius is labeled with its formal name. The inset shows an enlarged, enhanced view of Phobos, shaped rather like a potato with a hole near one end. The hole is the large impact creater Stickney, visible on the moon's upper right limb.

Spirit acquired these enhanced-brightness images with the Pancam on the night of sol 585 (Aug. 26,  2005). Scientists will use images of the two moons to better map their orbital positions, learn more about their composition, and monitor the presence of nighttime clouds or haze. Spirit took the six images that make up this animation with the Pancam broadband filter, which was designed specifically for acquiring images under low-light conditions.

Image credit: NASA/JPL/Cornell/Texas A&M

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This animation shows a large white dot against a black background, representing Phobos, moving from the lower center toward the upward right corner. Above and to the left of it is a smaller white dot, representing Deimos, that also moves upward and to the right but at a much slower pace. In fact, Phobos starts out below Deimos and quickly moves past it in the sequence. In the lower right quadrant, a small square insert shows an oblong, potato-shaped object, white against a black background, representing Phobos, with the upper right limb missing. The right side is also partially obscured by darkness. At the top of the image, the stars of the constellation Sagittarius are labeled, counterclockwise from upper left: Kaus Australis, Alnasl, Kaus Meridionalis, Kaus Borealis, Phi Sgr, and Nunki.