On Tuesday, February 12, 2019 at 6:09:25 AM UTC-7, Gerald Kelleher wrote:

The back and forth motion of the inner planets ( direct/retrograde motions) are
there before everyone based on the ability of a satellite to create a permanent
solar eclipse like conditions.

Of course, that ability is more theoretical than real.

For one thing, L1 is not stable, so the satellite would need a supply of
propellant.

For another, the earth-sun L1 point is about a million miles from the Earth, so
the satellite would only have to have four times the diameter of the Moon.

Of course, that _is_ irrelevant to the fact that the apparent motions of Venus
and Mercury show they orbit the Sun in much the same way as the apparent motions
of the Galilean satellites show they orbit Jupiter. That indeed is an insight
that is here to stay; I'd also like to say that it never went anywhere in the
first place since Copernicus, but given the reaction to your expression of that
insight, I'm beginning to wonder.

John Savard