<p><a href="http://science.nationalgeographic.com/science/space/solar-system/mars-article/">Mars' moon Phobos</a> is slowly crumbling, according to a new analysis. The grooves on the moon's surface are the first sign that it is being slowly pulled apart by tidal forces, NASA <a href="http://www.nasa.gov/feature/goddard/phobos-is-falling-apart">scientists announced</a> Tuesday.</p>

Tug of War

Mars' moon Phobos is slowly crumbling, according to a new analysis. The grooves on the moon's surface are the first sign that it is being slowly pulled apart by tidal forces, NASA scientists announced Tuesday.

Photograph by NASA/JPL-Caltech/University of Arizona

Week’s Best Space Pictures: Mars' Moon Phobos Slowly Crumbling

Winter comes roaring in on Saturn's moon Titan while a dead star rips apart a wandering asteroid.

Feed your need for heavenly views of the universe with our pick of the most awe-inspiring space pictures. This week, Hubble spies what could be the loneliest galaxy in the universe, and scientists try to make sense of a moon's stretch marks.

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