(Steve Willner) writes:

In article ,
Alain Fournier writes:
But as you have already pointed out, you really would want to do
computations using more than one body for this.

In principle, you need to take all bodies in the system into
account. Depending on the accuracy desired and on the masses and
distances, you may be able to ignore some of the least massive.

If you want to know which single body is the most influential, look
at references for "Hill Sphere."

Thank you! I hadn't encountered that term (no, I'm not even an amateur
astronomer), and what I found made for some interesting reading.