planetplanet

planetplanet is an open-source code for predicting and modeling planet-planet occultations, as well as transit and secondary eclipse light curves, phase curves, mutual transits, and more. In my 2017 paper (link below), I showed how planet-planet occultations are extremely common among the TRAPPIST-1 planets: on average, there is about one such occultation per (Earth) day(!) This happens because the TRAPPIST-1 system is extremely coplanar, and viewed almost perfectly edge-on from Earth. Most of these occultations are too brief and don't produce a detectable signal, but some occultations between planets b and c could be detectable with JWST and other upcoming telescopes. Check out the links at the top for the paper, the code, and the documentation.

Figure 1 Three years of planet-planet occultations in TRAPPIST-1, for a single random draw from the orbital parameter distributions. The system is seen from above, with the observer located towards the bottom of the plot and planets orbiting counter-clockwise. The initial orbital outlines of each of the seven planets are shown in grey, and each occultation is indicated as a colored circle placed at the location of the occulted planet at the time of the event. Circle colors correspond to different occultors: black is an occultation by the star (i.e., secondary eclipse), red is an occultation by b, and so forth (see legend at top left). Circle sizes are proportional to the event duration (legend at top right), and the opacity is proportional to the SNR of the occultation as seen by JWST/MIRI at 15 microns (legend at lower left). The "X"s indicate mutual transits, or planet-planet occultations occurring on the face of the star.