Can be analysed as an elastic collision (magnitude of difference in velocities before and after is the same (hyperbolic excess velocity)) (see IOAA 2016 team round)
<aside> 💡 If $M \gg m$, ****it can be assumed that, in the frame of reference of $M$, the total energy of $m$ stays constant. However, significant momentum will always be imparted to $M$. In other words, $V$ is insignificant, $MV$ is significant, and $MV^2$ is insignificant (where $V$ is the velocity of the large mass in the frame of reference of the large mass originally)
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Phase of a planet/moon is defined as the illuminated area divided by the total area of the limb (disc).
Related: Planetary magnitudes
Syncing of draconic and synodic month is an eclipse year/draconic year
Syncing of draconic, synodic and anomalistic month is a saros