  Most Sun-like stars in the Galaxy reside in gravitationally-bound pairs of
stars called "binary stars". While long anticipated, the existence of a
"circumbinary planet" orbiting such a pair of normal stars was not definitively
established until the discovery of Kepler-16. Incontrovertible evidence was
provided by the miniature eclipses ("transits") of the stars by the planet.
However, questions remain about the prevalence of circumbinary planets and
their range of orbital and physical properties. Here we present two additional
transiting circumbinary planets, Kepler-34 and Kepler-35. Each is a low-density
gas giant planet on an orbit closely aligned with that of its parent stars.
Kepler-34 orbits two Sun-like stars every 289 days, while Kepler-35 orbits a
pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. Due to
the orbital motion of the stars, the planets experience large multi-periodic
variations in incident stellar radiation. The observed rate of circumbinary
planets implies > ~1% of close binary stars have giant planets in nearly
coplanar orbits, yielding a Galactic population of at least several million.
