The People Who Named the Moon

This week, on September 25th, Japan marks Chushu no Meigetsu — the mid-autumn moon.

It is the moon of the fifteenth night of the eighth month in the old lunisolar calendar, long loved as the most beautiful moon of the long autumn nights.

In Japan, each night of the moon has its own name. Jugoya, Izayoi, Tachimachi-zuki, Imachi-zuki, Nemachi-zuki. The moon rises about fifty minutes later each night, so what changes is the posture of waiting. The moon you could wait for standing becomes the moon you wait for sitting, and then the moon you wait for lying down. The time spent waiting seems to have become the name itself.

The people who gave these names knew where the moon would rise, and from that decided how to spend the night. Knowing the position and putting it into the language of daily life were, it seems, continuous.

COCOIRO does the same thing.

We calculate where all ten bodies are right now, from the Sun to Pluto. We lay that over the sky at the moment you were born, turn it into today's words, and send one every morning.

A day that feels heavy for no reason, a day when you are unusually sharp — the sky has its reasons. We send those reasons, along with one thing worth keeping in mind today, like a letter.

Same sign, same birthday — but a different birth place or time, and different words arrive. What you take from them is yours.

Inside the app there is a screen that draws your birth chart, a table of where the ten bodies stand that day, and a moon calendar. The Japanese names above are one of the things shown in that calendar.

Izayoi is the moon of the sixteenth night counted from the new moon. The name is decided by the number of nights, not by the shape. This year the astronomical full moon falls on September 27th, two days after Chushu no Meigetsu. We show that gap as it is, without smoothing it over. The gap is the fact of that year's sky.

We do not translate these names in other languages either. Izayoi stays Izayoi, with the kanji and the reading beside it. Translated, it becomes "the hesitating moon" — a description rather than a name.

Planetary positions are calculated from a measured ephemeris. The exact moments of new, first quarter, full, and last quarter are computed to the minute and checked against published almanac values.

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