The Harvest Moon

September's full moon

The Harvest Moon by Catherine Hyde

September’s full moon will fall at 10.58am on 29th September. It is a super moon, the final one this year, super moons occurring when the moons closest point in its imperfect orbit, its perigee, coincides with it being full. A super moon looks up to 14% larger and 30% brighter than a micro moon, which is when the moon is full at its furthest point away from us, its apogee.

But perhaps more importantly this full moon is the harvest moon, one of the best known old moon names of the year. The harvest moon is one of very few that have specific timings attached, rather than roughly being allocated to various months: it is the full moon that falls closest to the autumn equinox. Because of this it can fall in September or early October, as this one very nearly does.

The harvest moon is among many old moon names relating to agricultural jobs, including March’s plough moon, April’s seed moon, May’s milk moon, July’s mead moon or hay moon and August’s grain moon, and the implication is of these jobs being so large and time consuming that the light of the full moon allowed people to continue on with them after nightfall.

The harvest moon is thought particularly large, bright, and orange, but is it? It certainly can be more orange in colour than most moons, particularly during a dry year and when it falls earlier in September, owing to the dust in the atmosphere from the wheat harvest. But its reputation for being larger seems to be more about timing than reality. There is a phenomena known as the ‘moon illusion’ whereby the moon looks much larger when it is close to the horizon than it does when it is high in the sky. The moment that the full moon rises above the horizon shifts all year - it is always around the same time as sunset. So in September this is around 7pmish, a time when quite a lot of people are still out and about, moving from work to home or from home to an evening out and so…they spot the moment of the moon rising in all its huge glory.

Anyway, look out for it, particularly as it pops above the horizon. Wishing you clear skies!

You can find all of your moon phases for the year ahead in my book, The Almanac 2024, in bookshops or via the links here

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