 And they occur almost all at the time of the monthly perigee when the Earth's gravity is strongest because you're closest to the moon. And when I first heard about that about 1976, and I'd only been at my studies for two years at that point, I thought, here's great corroboration. Again, I hear, well, come on, the Earth is 81 times as massive as the moon. So it's easy to see how the Earth's gravity could trigger moonquakes, but you couldn't turn that around.