From 4 million miles away on December 16, 1992, NASA's robot spacecraft Galileo took this picture of the Earth-moon system. Our moon is one of the largest moons in the solar system. It is even larger than the planet Pluto. In this picture, the Earth-moon system actually appears to be a double planet. The bright, sunlit half of the Earth contrasts strongly with the darker subdued colors of the moon. The terminator ("day-night-line") is much less sharp on earth because of atmospheric refraction ("twilight").