← Encyclopedia of Astrology · lesson 147/235
Gibbous Moon
What it is
A gibbous Moon is one that is more than half lit but not yet full — or, after the Full, no longer quite full. The word comes from the Latin gibbus, a hump, for its bulging shape: Nicholas deVore describes it as the phase in which "both sides are convex", unlike the half Moon with its one straight edge. Like the crescent, there are two gibbous Moons each month: the waxing gibbous before the Full Moon and the waning gibbous after it. This entry is about the first; the stretch after the Full belongs largely to the disseminating Moon.
Again the names come in two sizes:
- In the sky, the waxing gibbous Moon runs from the first quarter to the Full, from 90° to 180° ahead of the Sun, the whole second week of the cycle.
- In Dane Rudhyar's eight phases, the gibbous phase is the last 45° before the Full, from 135° to 180°, about ten and a half to fifteen days after the New Moon. It opens at the waxing sesquiquadrate (135°), a minor hard aspect, and closes at the opposition.
A waxing gibbous Moon rises in the afternoon and is high in the evening sky, brighter each night, until it rises at sunset as the Full Moon.
In the tradition
Older astrology did not give the gibbous phase a meaning of its own; for Ptolemy it is simply the second half of the waxing Moon's "hot" quarter, and for Lilly a Moon still increasing in light, which counts in her favour. Electional astrologers took note of it for a practical reason: Nicholas deVore's window for elections ends about three days before the Full, because a Moon too near the opposition is about to turn and begin to lose light. So the gibbous days have long been treated as good for pressing on with what is already under way, and less ideal for starting what must run long.
How it is read
The modern meaning comes from Rudhyar, who called the gibbous Moon the phase of evaluation and improvement. What was seeded at the New Moon, fought for in the crescent and built at the first quarter now exists; it is nearly whole, but not yet fully seen. The work of these days is to examine it, adjust it and make it better, so that it can stand in the full light that is coming. The mood is one of devotion and aspiration: Rudhyar speaks of a "yearning for more light".
For the person born in this phase, the gibbous type, he described "a desire to improve yourself and others, to evaluate things and people", to handle symbols of value, to bring a matter or a social trend to a conclusion, and devotion to a person or ideal held to be great. Later writers call it the analyst's or the perfectionist's phase: drawn to service and to contributing something of lasting worth, tempted by over-analysis, self-criticism and the feeling that it is never quite ready. (Some astrologers relate it to the waxing sesquiquadrate's sense of pressure: the strain of the last stretch before a result.)
In the month's rhythm the gibbous days are read as a time for polishing, checking and persevering rather than for new beginnings — the final edit before publication, the rehearsal before the night. Anything that comes to a head at the Full Moon is usually being shaped here.
The phase is measured by angle, not by appearance or by a calendar's label, so a Moon a calendar already calls "waxing gibbous" (past the quarter) may still be in Rudhyar's first quarter phase until it reaches 135°.