In the restricted form of this system, one of the masses is assumed to be negligibly small. For 10 points each:
[10e] Name this system that in general has no closed form equation of motion. The Earth, Sun, and Moon collectively form one of these systems.
ANSWER: three-body system [or three-body problem; prompt on n-body system or n-body problem]
[10m] Karl Sundman proved that there exists a power series solution to the three-body problem that converges except in cases where this quantity is zero. This pseudovector is perpendicular to the orbital plane.
ANSWER: angular momentum [prompt on L; do not accept "momentum"]
[10h] This astronomer names a parameter used to characterize orbits in the restricted three-body problem. His related namesake criterion can be used to determine whether two orbiting bodies observed at different times are the same.
ANSWER: Félix Tisserand [François Félix Tisserand]
<Kevin Ye , Science - Physics - Classical Mechanics>