(Steve Willner) wrote:

I had written:
Is the "heliocentric" idea this: we choose a coordinate system in
which angular momentum is minimized?

I don't think so. Minimizing angular momentum would give a rotating
coordinate system (non-inertial) with roughly Jupiter's rotation
period.

A heliocentric system is one in which the Sun's linear momentum is
zero. A "barycentric" coordinate system makes the net linear
momentum of the entire solar system zero.

Thank you! So a ----centric system sets *linear* momentum to zero.
This answers my supplementary question, which was:

Not being a physicist, I don't even know that my first assumption was
correct. When we make the origin of a coordinate system coincide with
the barycentre of a physical system of orbits, DOES that, in fact,
minimize angular momentum?

Odd that so few people bothered to jump on my erroneous assumption.