A team of European astronomers, including EXOEarths member Alexandre Santerne (CAUP), used the SOPHIE spectrograph at the Observatoire de Haute-Provence (France), to confirm the presence of Kepler-88 c, an unseen planet that was previously predicted thanks to the gravitational perturbation it caused on its transiting brother planet, Kepler-88 b.
Searching for periodic transits in hundreds of thousands of stars was the primary goal of the Kepler space telescope. More than 3,500 of such periodic transits were found during the 4 years of the mission. However, not all the planets located in the Kepler field-of-view are transiting their host star. Indeed, if their orbital plane is slightly misaligned (only a few degrees is enough) with the line of sight from the Earth, the planet is not transiting and, thus, is “unseen” from the Kepler spacecraft.
Read more at: http://phys.org/news/2013-12-unseen-exoplanet.html#jCp