Astonomy vs. Physics

"...the body of the Earth, large, sluggish and inapt for motion is not to be disturbed by movement..."
(Crowe 140 quoted from Brache)

If the Earth is too large, too sluggish for motion, how large are the other planets in Brache's system? How large are the sun and the moon? He can't think that we see the celestial bodies in real size, but they can't be very large in his mind. This kind of goes with the idea that the universe is small.