# Overview¶

The planetplanet software package was designed to compute light curves of planet-planet occultations (PPOs) in exoplanet systems. During a PPO, a planet occults (transits) the disk of another planet in the same system, blocking its thermal (and reflected) light, which can be measured photometrically by a distant observer. We developed this package with the TRAPPIST-1 planetary system in mind, but planetplanet is generally applicable to any exoplanet system.

Because of the general way in which planetplanet computes occultation light curves, it natively supports the computation of transit light curves, secondary eclipse light curves, and planetary phase curves, as well as occultations of planets by moons and mutual transits of planets across the face of their host star. Check out our paper for more information.

This documentation explains how to install the code and use it to compute light curves for TRAPPIST-1 and other exoplanet systems. Check out the tutorial for a quick guide on how to use the code and the scripts page for additional examples and code to reproduce several of the figures in the paper. Finally, the API section contains detailed descriptions of the Python and C planetplanet backends.