Colorful Aurora

Saturn's aurora, the equivalent of the northern and southern lights on Earth, forms a green ring about the planet's south pole in this recent false-color image from the Cassini spacecraft. The image is compiled from observations at infrared wavelengths, which are invisible to the human eye. Heat from deep inside backlights storm systems and cloud bands in the upper atmosphere, forming dark silhouettes. The aurora, which is about 600 miles (1,000 km) high, forms as energetic particles from the Sun strike atoms high in the planet's atmosphere. [NASA/JPL/Univ. Arizona/Univ. Leicester]