the year 2027

Full moons of 2027: all twelve, to the hour and minute

A full moon is not a day, it is an instant. Here is when each of the twelve arrives, in which sign, and why January goes almost three weeks without one.

A full moon is not "the night the Moon looks round". It is the instant the difference between the Moon’s and the Sun’s longitudes passes exactly 180 degrees: the Earth comes between them, and the lit side of the Moon faces us completely. The instant is one for the whole planet. Only our clocks differ.

Why January has a three-week gap

The first full moon of the year is not until 22 January. The previous one was 13 December 2026, and between them lies exactly one lunar month — twenty-nine and a half days. The calendar year simply started at an awkward point: had it begun a week earlier, it would have held thirteen full moons. So "thirteen full moons" is a property of the calendar, not of the sky.

The sign of a full moon is the sign opposite the Sun

Look down the list: January’s full moon is in Leo, and the Sun is then in Aquarius; July’s is in Capricorn, and the Sun is in Cancer. This is always so, because a full moon happens opposite the Sun by definition. It is worth knowing: if a page tells you there is a full moon in Cancer in July, it is wrong, and the rest of that page is not worth checking.

Where these hours come from

The longitudes of the Moon and the Sun are computed from orbital elements published by NASA JPL — by the same code that runs every reading on this site. The instant of the 180-degree crossing is narrowed by bisection. All twelve agree with the published full-moon calendar to within two minutes.

Times are GMT. The full moon of 20 May at 11:00 GMT is 5:00 in the morning in Calgary the same day; the full moon of 19 June at 00:46 GMT is already the evening of 18 June there. So "full moon on 19 June" and "full moon on 18 June" can both be true at once.

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