30
Resonances: Properly timed gravitational
“pushes”
•Like
someone pushing kid on a swing
–Timing
of pushes just as important as force used
•Pushing
at random times has little effect
•Pushing
at just right point in each cycle can produce big effect
•Resonances are same sort of effect – for orbits
•If orbital periods have ratio 1:2, moons pass each other
in same place
each orbit, so gravity of one on other badly disturbs orbit
each orbit, so gravity of one on other badly disturbs orbit
Io : Europa orbital periods
1.7 days : 3.4 days
1.7 days : 3.4 days
1 :
2