Full moons and new moons

A full moon or a new moon is not “somewhere around mid-month” — it is an exact moment. A new moon arrives when the angle between the Sun and the Moon, seen from Earth, becomes exactly 0°; a full moon, when it becomes exactly 180°. That moment is the same for the entire planet: the phase happens simultaneously in Moscow, London and Sydney, and only the reading on the clock differs. That is why every event below carries not just a date, but an hour and a minute.

Between two identical phases lies a synodic month — on average 29 days 12 hours 44 minutes. “On average” is doing real work here: the actual interval drifts between 29.27 and 29.83 days, because the Moon's orbit is an ellipse and its speed varies from 11.8 to 15.4 degrees a day. That is why a calendar of phases cannot be built by simple addition: every new moon has to be computed separately. Which is exactly what happens here.

Astrologically, a new moon is the point where the Sun and the Moon stand at the same degree of the same sign: for the first time in a month, conscious intention and emotional need are looking in the same direction. It is the start of a cycle, a time to formulate rather than to take stock. A full moon is the opposite pole: the Moon lands in the sign across from the Sun, and whatever has been ripening for two weeks becomes visible. Hence the full moon's reputation as the time when “everything comes out” — not mysticism, just maximum contrast between the two halves of the chart.

The sign and degree in the table are the Moon's position at the exact moment of the phase. At a full moon the Sun automatically stands in the opposite sign: Moon in Cancer means Sun in Capricorn. At a new moon both luminaries share one sign and one degree. The degree matters if you have your own chart: a phase that falls within two or three degrees of one of your planets, or of a chart angle, works noticeably harder than the general background does.

A year normally holds 12 full moons — one a month. But the synodic month is almost a full day shorter than the calendar month, so every two or three years a thirteenth accumulates: two full moons land inside a single calendar month. The second of them is called a blue moon, although colour has nothing to do with it. Such months are visible straight from the table: they carry two “Full Moon” rows.