Where does Kepler orbit?
Kepler is in a heliocentric (Sun-centered) orbit. Kepler’s orbit was chosen to enable continuous observation of the target stars. This requires that the field of view of Kepler never be blocked. For a spacecraft in low-Earth orbit, nearly half of the sky is blocked by the Earth and the obscured region is constantly changing. The most energy efficient orbit beyond Earth orbit is a heliocentric (Sun centered) Earth-trailing orbit. An Earth-trailing heliocentric orbit with a period of 371 days provides the optimum approach to maintaining a stable trajectory that keeps the spacecraft within telecommunications capability. Another advantage of this orbit is that it has a very-low disturbing torque on the spacecraft, which leads to a very stable pointing attitude. Not being in Earth orbit means that there are no torques due to gravity gradients, magnetic moments or atmospheric drag. The largest external torque then is that caused by light from the sun. This orbit also avoids the high-radiatio
