I love this fact — and it’s true even though the Sun’s gravitational force on the Earth (and its oceans) is far greater than that of the Moon. It’s true because a uniform gravitational force would not cause any tides at all — what causes tides is the gradiation in the gravitational force, and that’s much greater for the moon because it’s a lot closer.

The Sun completely dominates this whole area of space, gravitationally — in fact, the Moon doesn’t really rotate around the Earth but around the Sun, it is merely gravitationally coupled with the Earth, so from our perspective it appears to rotate around us, when we are both primarily rotating around the Sun while holding hands.

As proof of that last fact, I would point out that the Moon’s rather complex trajectory with respect to the Sun is never convex, never accelerating away from the Sun, but always concave.

Thanks for an excellent article, I just wanted to channel Isaac Asimov (who taught me all this) a bit.