Moon Phase vs Sun-Moon Aspects: Phase Sectors and Aspect Orbs

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The Sun and Moon give two different readings in a natal chart. One is the aspect between them, if there is one: a conjunction, sextile, square, trine or opposition. The other is the Moon phase. Both come from the same two positions, so they are easy to treat as one thing, but they use different measurements and different boundaries. This page sets them side by side so that each can be read on its own terms.

Calculator note: The Astrologist.com birth chart does not calculate or label Moon phases. It shows the Sun and Moon by sign, degree and minute, and the phase described here is worked out by hand from those two positions. Without a birth time, the chart places the Moon at local noon as a date reference only, so a phase read from that position is not established until the whole birth date has been checked.

Two measurements of one pair

An aspect uses the separation between the Sun and the Moon: the shorter way round the circle, from 0° to 180°. It does not care which body is ahead. The free chart draws a Sun-Moon aspect line when that separation is within the standard orb of an exact angle: 8° for the conjunction, square, trine and opposition, 6° for the sextile, the same flat orbs used for every pair of planets.

A phase uses the directed elongation: the Moon's longitude minus the Sun's, counted forward and taken modulo 360, from 0° to just under 360°. It always knows which half of the cycle the Moon is in. The circle is cut into eight fixed sectors of 45°, starting at 0°, and there is no orb. Natal Moon phases explained covers the sectors and their names.

So an aspect answers "how far apart, near which exact angle?" and a phase answers "where in the cycle, going which way?".

How the orbs fall across the phases

Every aspect except the conjunction and the opposition can form twice in a lunation, once while the Moon is waxing and once while it is waning. Here is where each orb window lands in directed elongation (E), using the free chart's orbs:

Two kinds of boundary meet in this table. Orb limits are inclusive: a separation exactly 8° from the exact angle still counts as in orb. Phase sectors are half-open: each starts at its lower boundary and stops just short of the next, so 90° itself is First Quarter, not Crescent. The opposition is one continuous orb from 172° to 188°; the table splits it at 180° into its waxing portion, in the Gibbous phase, and its waning portion, in the Full phase. The conjunction's waning window stops just short of 360°, because 360° is the same point as 0°, the exact New Moon, which belongs to the New phase. Read the table this way: a conjunction can belong to the New or the Balsamic phase, a square or opposition can sit in either of two phases, and the sextile and trine each have a waxing and a waning version in different phases. No aspect tells you the phase on its own, and no phase guarantees an aspect.

Most charts have a phase but no Sun-Moon aspect

Every birth has a phase. A Sun-Moon aspect needs the separation to fall inside one of the orb windows, which together cover 120° of the 360° cycle. In a sample of London noon charts from 1900 to 2099, calculated with the free chart's routines, 33.2% had a major Sun-Moon aspect within orb. The other two thirds had none, and the phase is still there to describe how the two lights relate.

Four calculated examples

These charts were calculated with the free chart's routines; positions are as the planet table displays them, and the people are fictional.

• Manchester, 10 July 1987, 21:00. Sun 18°01' Cancer, Moon 13°31' Capricorn. Separation 175.5°, so the chart draws an opposition line. Directed elongation 175.5°: Gibbous. The Moon had not yet reached the Full Moon, which was still about seven and a half hours away.
• Dublin, 11 January 1990, 12:00. Sun 21°00' Capricorn, Moon 24°47' Cancer. Separation 176.2°, also an opposition line. Directed elongation 183.8°: the Full phase. Two opposition lines, two different phases.
• Glasgow, 11 June 1993, 21:00. Sun 20°53' Gemini, Moon 16°30' Pisces. Separation 94.4°, a square line. Directed elongation 265.6°: Disseminating, not Last Quarter. A waning square is not always a Last Quarter birth.
• London, 8 April 1987, unknown time. Running the chart at 00:00 and 23:59 gives elongations of 107.9° and 118.9°, so the phase is First Quarter all day. The trine, however, only came into orb at 112° at about 09:01 local time (BST). For this date the phase is settled without a birth time while the Sun-Moon trine is not, which is why the free chart leaves Moon aspect lines off an unknown-time chart.

Do not count the same geometry twice

When a chart has both a Sun-Moon aspect and a phase, they are two descriptions of one relationship, not two independent pieces of evidence. A waxing square in the First Quarter phase does not make a theme of effort "doubly" present. Read the aspect for the quality of the angle and the phase for its place in the cycle, and let them qualify each other.

The existing aspect pages describe the angles themselves:

• Sun conjunct Moon: births within 8° of the New Moon, on either side.
• Sun sextile Moon: an easy angle that falls in the Crescent or the Last Quarter phase.
• Sun square Moon: around the First and Last Quarter Moons.
• Sun trine Moon: inside the First Quarter or Disseminating phase.
• Sun opposite Moon: births within 8° of the Full Moon, on either side.

The phase pages, born under a waxing Moon and born under a waning Moon, add the direction those pages leave out.

Same sign is not the same phase

Signs add a third layer that is easy to confuse with the other two. The Sun and Moon in the same sign can be a New phase or a Balsamic one, depending on which is ahead; in the London noon sample, 50.2% of same-sign dates were Balsamic. A Sun-Moon conjunction can also join two different signs, for example the Sun at 28° Aries and the Moon at 2° Taurus. Work from the degrees, not from the signs, for both the aspect and the phase.

Checking your own chart

On the free birth chart, look for a line between ☉ and ☽ on the wheel; that is the aspect, if there is one. For the phase, take the two positions from the planet table and follow how to find your natal Moon phase. If the birth time is unknown, there will be no Moon aspect line, and the phase needs the full-day check on Moon phase without a birth time. More on how orbs work is on aspect orbs.

Related articles

• Natal Moon Phases Explained
• How to Find Your Natal Moon Phase
• Major Aspects in Astrology
• Aspect Orbs in Astrology