Rogue Planet Montage Free-floating planets wander alone in space. Perhaps they were ejected from the planetary system in which they formed, or maybe they never were gravitationally bound to a star.
Kepler's Worlds On March 6, 2009, the Kepler spacecraft zoomed into the night sky over Cape Canaveral, Florida, on an enormously successful mission to detect extrasolar planets. Over 3,500 possible alien worlds have been found. Many others likely are within the instrument's vast datasets, waiting to be discovered.
Binary Red Dwarf Star System A planet existing in the habitable zone of a binary red dwarf star system could look similar to this one. The planet is tidally locked with the eclipsing red dwarf stars. Cloud patterns originate at the substellar point, radiating outward toward the dark side of the planet. Flares from the stars are reflected in the water of the lit side. The polar cap on the dark side is illuminated by the white dwarf in the distance. An asteroid passing by is shown in the foreground. Red dwarf stars are common in the universe and a planet could exist orbiting one or more of them.
Carbon Planet Astronomers suspect that some extrasolar planets may be made largely of carbon compounds, including diamond. This is unlike Earth, Mars, and Venus, which are composed mainly of silicon-oxygen compounds. A world like this might have a thin, smoggy atmosphere and a surface resembling tar. Here a large impact crater exposes the diamond layer.
Terrestrial planets looking like this one may exist around M stars. This world is locked in rotation with its star and is located at just the right distance from the M star to create different zones around the substellar point like the rings on a target. The zones closest to the star are too hot and dry for life and the zones near the terminator are too cold, leaving an area in-between where temperatures are just right.