Uranus, the solar system's third-largest planet, is an almost featureless ball in this 1986 image from Voyager 2, the only spacecraft to visit it. Methane in the upper atmosphere absorbs red wavelengths of light, producing the planet's color. Uranus is at its best for the year in late October, when it lines up opposite the Sun. Although it will shine at its brightest, you still need binoculars or a telescope to see it. [NASA/JPL]