On its 449th martian day, or sol (April 29, 2005), NASA’s Mars rover Opportunity woke up approximately an hour after sunset and took this picture of the fading twilight as the stars began to come out. Set against the fading red glow of the sky, the pale dot near the center of the picture is not a star, but a planet — Earth. Earth appears elongated because it moved slightly during the 15-second exposures. The faintly blue light from the Earth combines with the reddish sky glow to give the pale white appearance.