Supermoon Seasons

The nearest full Moon of the coming year: a supermoon. Its tag says how far away it is and how wide that makes it look. The ring is a fixed size, and the disc nearly fills it. The next step draws the same ring.

The farthest full Moon of the year, in the same ring: now it sits loose inside. Compare the tags — the nearest full Moon is about a seventh wider. Months apart, with nothing to measure against, hardly anyone can tell.

Two and a half years of the Moon's distance. It swings in and out every 27.55 days, perigee to perigee; the dots are the full Moons, every 29.53 days. The two clocks don't match, so each full Moon lands two days later in the swing.

Join the full Moons and a slow wave appears: the full Moon drifts through perigee once every 411.8 days. Each trough is a run of supermoons, nearly always three in a row. Not rare, just bunched.