Kepler's New Mission: To Hunt Strange Orphan Worlds
This is an artist's impression of an orphaned or "rogue" planet — a world that has become excited from its parent star and is drifting through interstellar space.
Credit: NASA/JPL-Caltech

After an unprecedented survey to look for Earth-like planets beyond the solar system, NASA's Kepler space telescope this week begins a search for free-flying planets to learn just how common orphan worlds may be.

Planets without host stars are difficult to find, but they do exist. Scientists believe these bodies were ejected from their solar system families due to gravitational dynamics, lured away by tidal forces from interloping passersby, or perhaps even formed without the benefit of a parent star. What they don't know is if orphan planets are common or not.

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