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.
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.