Tiny Martian moon Phobos, caught transiting the face of Mars by the European Space Agency’s Rosetta probe on February 24, 2007. Phobos is near the center top of the image, casting a shadow on the planet near the top left corner, and near the U-shaped crater that will be the landing site of NASA’s Curiosity Rover (image credit: ESA/Reprocessed by Gordan Ugarkovic).