To quote Bouw:

"Here it is for the simple ones (Proverbs 1:22). For the sake
of this illustration we shall call the north ecliptic pole "up."
Then, because the Cassini craft is carried about the earth by
the gravitational field of the cosmos (firmament), Cassini
will see the earth move from left to right past the sun when
the sun is behind the earth and then see the earth returning
from right to left behind the sun. Cassini's distance
from the sun will remain about the same, changing only by the
craft's own intrinsic motion relative to the sun, but its
distance from earth will vary sinusoidally with a total
amplitude of 2 a.u.

When men like Fred Hoyle and Bertrand Russel say that there is
no physical difference between the Copernican and Ptolemaic
or Tychonic models, they mean it. What's so hard to understand
about that?"!

Dunash

That post seems like it would fit in the other thread about Cassini, especially in answer to my first question there. Still, I'm unclear as to who is making the challenge, and what the challenge is exactly.

By no physical difference, you mean that any frame of reference, rotating or not, is equivalent to any other? And so there is no intrinsic difference between the Copernican system and the Ptolemaic system? Even Einstein said that, and Born too.