The tree keeps growing
A limb that is a hand span across when a fixture goes up will not be that size in five
years. Anything that grips it will be gripping harder every season, and a cable pulled
tight along the trunk will be tighter still. So the fixture is held in a way that leaves
the limb room, the cable is run with slack at every point where the tree moves, and both
are looked at again as the tree fills out.
A route that cannot be seen
The cable has to get from the ground to the canopy. It goes up the side of the trunk
that faces away from the house and the seating, follows the line of the bark, and
reaches the fixture along the top of the limb, where it is invisible from below. A
moonlight that works beautifully at night and shows a black wire up the trunk all day
is half a job.
If you can see the lamp from your chair, it is not moonlighting. It is a light in a tree.
Reachable, or it is the wrong place
A fixture high in a tree will need attention one day: a branch grows across it, a
storm turns it, a lens films over. If the only way back to it is a crane, it will be
left. The position is chosen for the pattern it gives and for being reachable again, and
where those two pull apart, reachable wins.
If you have concerns about a particular tree, it is worth asking your arborist to look
at the mounting plan as well. They know the tree; we know the light.