The full eclipse of the moon is kind of educational. Even with unremarkable binoculars, it is clear that the earth is not that much bigger than the moon. When the earth’s shadow roughly bisects its satellite, which will be full later today, one can see that the segment of the earth projected on the moon is about a seventh or eighth of the earth’s circumference. That is, the diameter of the earth is twice or thrice that of the moon. To wit, the earth’s satellite is quite a giant in relative terms. Somehow, this has never penetrated through my thick skull even though I have long known that the moon’s gravity is roughly a sixth that of the earth. Which means that the volume of the satellite is about a sixth of the volume of the planet it orbits. An excellent example of abstract knowledge, I reckon.