From space, Earth's swirling white clouds reveal an often-turbulent atmosphere. The browns are landmasses, but mostly we see the blue of a planet covered with oceans of water. As nightfall sweeps westward across its face, the land begins to glow with lights—we can see ourselves.         Earth. Computer-generated image created using GOES-8 imagery. ARC Science Simulations. ©2000.           Giant Jupiter looms in the sky above its moon Io. An erupting volcano on Io's horizon sends a plume hundreds of miles into space. The eruptions mottle Io's surface with multicolored deposits of sulfur and lakes of lava.         Jupiter above Io. Computer-generated image created from Voyager and Galileo data. ARC Science Simulations. ©2000.

Mercury has virtually no air to scatter sunlight and color its sky. Even in daylight, if you face away from the blazing Sun, the sky appears black and dotted with stars. Sometimes visible among them are a blue speck and its tiny companion—Earth and its Moon.         Mercury. Marine 10 mosaic from 1974 with colorization by ARC Science Simulations.