Rotation, rotation, rotation!

Can prim A rotate on its axis while rotating around prim B, which is rotating on its axis while also rotating around prim C, which in its turn would be rotating on its axis?

I only ask because I'm thinking of building an orrery.

The horrory!

I think you can get away with A and B (llTargetOmega() on a child prim and on the root prim), but not with three levels unless you carefully calculate the motion yourself (and in that case it MAY not always be very smooth unless you do it slowly and with physical objects).

Not all linked together in the same object. What you are talking about is called "hierarchical linking" support, and SL doesn't have it yet. It's on the "pony list", though.

You can easily make a solar system with a star and planets with different orbits (and axis rotational periods). However, you will have a hard time adding moons or other planetary satellites to the mix.

Thank you both for your advice.

"Pony list"!? Charming expression.

for your third level you could use particles possibly (may be kinda jumpy) or a follower type setup where the child object reports it's next (or even current) position to an unlinked follower which updates it's own position based on that

Sadly, particles can't really be made to "orbit" anything by themselves (oh how I wish they could! :-/ ), so that's likely a non-starter.

The rest ends up just being a discrete / brute force movement engine, either physical, using llApplyImpusle/llSetForce/llMoveToTarget, or nonphysical, using llSetPos/llSetRot. In both situations, it would be lag-sensitive, tend to be rather jerky movement, and fairly significant in the script execution time area.

That said, Jeffrey Gomez has a fairly decent physics-based solar system model (the Sun is a particle emitter, too!), and it does model the Moon. Might be a starting point if you are interested in investigating that angle.

How significant is the question of linking in this case?

I ask because one approach I am considering is to build to some approximation of scale, in which case the objects would be too far apart to be linked. I could of course link the smallest prim (10cm) of the Moon to Earth then but how would its independent rotation be affected? And could the other planetary models rotate around the largest prim, the Sun, without being linked?

If not, I would build to a much smaller size and dismiss the notion of approximating scale.

particle at a distance from the emitter, rotate the emitter, can be a colocated prim, or the actual prim with some texture animation for it's own rotation.