For anyone else wondering whether the "keyhole" term was made up for this or not, no: https://en.m.wikipedia.org/wiki/Gravitational_keyhole https://en.m.wikiped

For anyone else wondering whether the "keyhole" term was made up for this or not, no: https://en.m.wikipedia.org/wiki/Gravitational_keyhole https://en.m.wikipedia.org/wiki/Gravitational_keyhole