Kepler-19 The "invisible" world Kepler-19c, seen in the foreground of this artist's conception, was the first world discovered solely through its gravitational influence on the companion world Kepler-19b, the dot crossing the star's face. Kepler-19b is slightly more than twice the diameter of Earth, and is probably a "mini-Neptune." At the time of its discovery, nothing else was known about Kepler-19c, other than that it existed, but followup observations yielded more information. David A. Aguilar (CfA)