Sagittarius Moon and Aquarius Moon compatibility links a fire sign and an air sign, two signs apart. That gap is a sextile, one of the friendly angles on the old list. Between the two signs lies Capricorn, and with it the winter solstice.
That middle sign is the key to this page. In the Tetrabiblos, the Greek astronomer Ptolemy says some pairs of signs “behold” each other across a solstice. Read by whole sign, as his translator Frank Robbins sets it out, Sagittarius and Aquarius are one of those pairs. Read by degree, as William Lilly did, they are not. We give both readings below.
First, a plain note. Astrology is not a science. No study has shown that Moon signs predict how a couple will fare. Read what follows as a lens, not as a forecast.
The pair at a glance
| Question | Short answer. |
|---|---|
| Distance between the signs | Two signs, a sextile of 60 degrees. |
| Elements and modes | Fire and mutable, air and fixed. |
| Kind of sign | Both day signs, which Ptolemy calls masculine. |
| Moon strength | No major rank in either sign. |
| Rulers | Jupiter for Sagittarius, Saturn for Aquarius. |
| Do the signs behold each other? | Yes by whole sign, no by degree. |
| How common is the pair? | About 1 couple in 72, like any pair of two signs. |
| How close is the sextile? | Within 8 degrees in 46 percent of couples. |
What a Moon sign shows
Your Moon sign is the sign the Moon stood in at your birth. Astrologers read it as your inner weather. It shows what calms you, what hurts you, and how you look after people.
Two Moons are compared by counting the signs between them. Sagittarius and Aquarius sit two signs apart, which makes a sextile. Ptolemy lists the sextile with the trine as a friendly angle. Our moon sign compatibility guide goes through every distance, from the same sign to the opposite one.
Fire feeds air
Fire is the element of heat, drive and spirit. Air is the element of thought, talk and links between people. In the old scheme, fire and air get along. Air feeds a flame, and fire warms the air. Both are day signs, so both Moons want to show and share what they feel.
The modes add contrast. Sagittarius is mutable: it bends, adapts and moves on. Aquarius is fixed: it holds a course and keeps it. The fire Moon changes its mind when it learns something new. The air Moon keeps its view until the facts force a change.
Only two of the 78 Moon pairs have this exact mix: a fire and air sextile, one mutable sign and one fixed. The other is Gemini with Leo, the mirror of this pair across the summer solstice. Our page on Gemini Moon and Leo Moon compatibility covers it.
In a good week, the match feels light and wide. Both love ideas, both want room, and neither clings. In a hard week, both talk about feelings in place of feeling them. One jokes, one goes cool, and the hurt waits.
Two Moons with no rank
Tradition gives each planet four special signs. The home is the sign it rules. The exaltation is where it is an honored guest. Across from these sit the exile and the fall. For the Moon, the home is Cancer and the exaltation is Taurus. Its exile is Capricorn, and its fall is Scorpio.
Neither Sagittarius nor Aquarius is on that list. A planet with no major rank in a sign is called peregrine, from a Latin word for a traveler. It gets no help and no harm. Each sign does give the Moon one small slice, a ten degree span called a face. In Sagittarius, it is the middle ten degrees. In Aquarius, it is the last ten. The old authors gave faces little weight.
So both partners carry a traveling Moon. The Sagittarius Moon settles by moving toward something new. Our page on the Moon in Sagittarius looks at that seat. The Aquarius Moon settles by stepping back to think. Our page on the Moon in Aquarius covers that one. Neither starts from a strong seat, and neither from a weak one.
Jupiter and Saturn, the two hosts
Each Moon answers to the ruler of its sign. In the old scheme, Jupiter rules Sagittarius and Saturn rules Aquarius. Modern astrologers add Uranus for Aquarius, but the ranks below come from the older list.
Jupiter is the planet of faith, growth and good luck. Saturn is the planet of limits, time and structure. The fire Moon hands its moods to Jupiter, so a low mood turns into a search for meaning. The air Moon hands its moods to Saturn, so a low mood turns into distance and a cool head.
Neither host holds a major rank in the other’s sign. Jupiter owns only a small span of degrees in Aquarius, called terms. Saturn owns a small span of terms in Sagittarius. So the hosts neither honor nor harm each other. The bond rests on the sextile and on the tie Ptolemy names.
Do Sagittarius and Aquarius behold each other?
In Book 1 of the Tetrabiblos, Ptolemy names signs that “behold” each other, or have “equal power”. The rule is a mirror around a solstice. Two signs behold each other when they sit the same distance from it, one on each side. Their days then have the same length. The solstice signs are Cancer, at midsummer, and Capricorn, at midwinter.
The question is where you draw the mirror line. There are two answers, and they give different pairs.
| Way of reading | Where the mirror line sits | What it says about this pair. |
|---|---|---|
| By whole sign | Through the middle of Capricorn, which is left alone | Sagittarius and Aquarius behold each other. |
| By degree | At 0 degrees Capricorn, the solstice point | Sagittarius mirrors Capricorn, and Aquarius mirrors Scorpio. |
The whole-sign list comes from the notes of Robbins’s 1940 translation. His note 83 gives five pairs: Gemini and Leo, Taurus and Virgo, Aries and Libra, Pisces and Scorpio, Aquarius and Sagittarius. Cancer and Capricorn have no partner. Count out from Capricorn and you see why. Sagittarius is one step before it, and Aquarius is one step after. They are the closest pair on the winter side.
The degree reading is the one Lilly used in Christian Astrology. He called these mirror points antiscia. A planet at 10 degrees Sagittarius has its mirror at 20 degrees Capricorn, not in Aquarius. By degree, the two Moons only meet in the mirror when both sit right by the edge of Capricorn. With a 3 degree margin, that happens to about 1 couple in 200.
So which is right? Both readings are old, and this page does not pick one. By whole sign, the pair has a tie beyond the sextile. By degree, the sextile stands alone. Ptolemy’s other quiet tie, where one sign “commands” another, does not join these two on either reading. By whole sign, in his note 80, Leo commands Sagittarius and Gemini commands Aquarius.
Is the sextile exact?
A sextile by sign is not always a sextile by degree. Take a Sagittarius Moon at 1 degree and an Aquarius Moon at 29 degrees. They are two signs apart, but the true gap is 88 degrees. That is nearly a square, a tense angle. Astrologers allow some slack around the exact angle, called an orb.
| Orb allowed | Share of couples with a true sextile. |
|---|---|
| Within 3 degrees | 19 percent of couples. |
| Within 6 degrees | 36 percent of couples. |
| Within 8 degrees | 46 percent of couples. |
| Within 10 degrees | 56 percent of couples. |
These shares are the same for every Moon pair, because the Moon spends close to the same time in each degree. With an 8 degree orb, fewer than half of these couples have an exact sextile. In about 3.6 percent, the Moons form a square across the sign line instead.
The sextile least tied to the new moon
A person born with the Moon and the Sun in the same sign is a new moon birth, by sign. A person born with the Moon across from the Sun is a full moon birth, by sign. For exact phases, see our page on moon phase compatibility.
| Moon sign | New moon births, Sun in the same sign | Full moon births, Sun in the opposite sign. |
|---|---|---|
| Sagittarius Moon | 7.96 percent, Sun in Sagittarius | 8.44 percent, Sun in Gemini. |
| Aquarius Moon | 7.97 percent, Sun in Aquarius | 8.43 percent, Sun in Leo. |
The cause is the speed of the Sun. Earth is closest to the Sun in early January. So the Sun moves fast through the winter signs, and the Moon has fewer days to join it there. Earth is farthest from the Sun in early July. So the Sun moves slowly through Gemini and Leo, and the Moon has more days to face it.
In a couple, the two leans add up. Only 15.3 percent of these couples include a new moon birth. That is the lowest of all twelve sextile pairs. On the other side, 16.16 percent include a full moon birth, 5th of 78 pairs.
If your Suns sit in these signs too, see our page on Sagittarius and Aquarius Sun sign compatibility.
How common is the pair?
The Moon gives each sign almost the same share of its time. From 1600 to 2400, each sign holds between 8.331 and 8.336 percent. So any pair of two different Moon signs turns up about 1 time in 72. A same-sign pair turns up about 1 time in 144. We do not rank Moon pairs by how common they are. The gaps are smaller than the error of our method.
Confirm both Moons
The Moon is quick. It spends about 54.6 hours in a sign on average, and anywhere from 46.9 to 61.1 hours. So the Moon changes sign on 43.92 percent of days. For people born on those days, only the hour decides the Moon sign.
Many free charts fill a missing birth time with noon. That guess names the wrong Moon sign for 10.98 percent of people, about one in nine. For a couple, two noon charts give the wrong Moon pair 20.75 percent of the time, about one couple in five. Only about 31 percent of couples have both Moons settled by their dates alone.
A noon chart that says Sagittarius Moon could hide a Capricorn Moon for someone born late in the day. A noon chart that says Aquarius Moon could hide a Capricorn Moon for someone born early. Both errors land on the sign in the middle.
How we got these numbers
Every figure here comes from two methods that share no code. The first used the Astronomy Engine library. It found each time the Moon and the Sun changed sign from 1600 to 2400, to a tenth of a second. It then added up the hours. The noon test used a chart cast at 12:00 UTC each day.
The second method used the Swiss Ephemeris, a separate set of star tables. It checked the Moon’s sign once an hour over the same eight centuries, on a grid offset by half an hour. That gives more than seven million checks. No random draws were used. The two methods agree within 0.04 points on every Moon figure here. All values use the tropical zodiac, as seen from Earth.
What the evidence says
The largest test of star-sign matches used the 2001 census of England and Wales. The sociologist David Voas studied 10.3 million married couples in a 2007 paper, “Ten million marriages”. Sun signs had no effect on who married whom. A small excess of couples sharing a sign traced back to errors in the data. His test covered Sun signs only. No test of that size exists for Moon signs.
So the sextile is not a promise, and Ptolemy’s tie is not proof. They are symbols. These two Moons both need space and both love ideas. The symbols show where that shared freedom helps, and where it needs warmth said out loud.
Habits that suit this pair
These follow the symbols. They are not rules.
- The Sagittarius Moon stays with a hard feeling for one full talk before it jokes.
- The Aquarius Moon says “I feel” before it says “I think”.
- Both plan time apart on purpose, so space is a choice and not a retreat.
- Both give one small, plain sign of care each day, since ideas alone do not warm a home.
Other pairs to compare
The Venus side of this pair is covered in Sagittarius Venus and Aquarius Venus compatibility. Another fire and air sextile, with Aries, is in Aries Moon and Aquarius Moon compatibility. For the sign between these two, see Sagittarius Moon and Capricorn Moon compatibility.
Frequently asked questions
Are a Sagittarius Moon and an Aquarius Moon compatible?
Astrology reads them as a fire and air sextile, a friendly angle between two day signs. One Moon adapts and the other holds firm. No study has shown that Moon signs predict a couple’s future, so treat this as a lens.
Do Sagittarius and Aquarius behold each other in Ptolemy?
By whole sign, yes: Robbins’s note 83 lists Aquarius and Sagittarius as a pair. By degree, as Lilly read it, no: Sagittarius mirrors Capricorn, and Aquarius mirrors Scorpio.
Is the Moon strong in Sagittarius or Aquarius?
Neither. The Moon has no major rank in either sign, which the old books call peregrine. It owns only a minor ten degree face in each.
How common is a Sagittarius Moon and Aquarius Moon couple?
About 1 random couple in 72. The Moon spends almost the same time in each sign, so every pair of two different Moon signs has the same odds.
Do I need a birth time to know my Moon sign?
On many days, yes. The Moon changes sign on 43.92 percent of days. A noon guess is wrong for about one person in nine, and for about one couple in five.
Go deeper with your personal Astrovision report
Reading about astrological concepts is a great start, but nothing compares to hearing how they apply directly to you. Our users love our audio-first approach, calling it “friendly, personal, and easy to understand.” While this article gives you the “what,” a personal report gives you the “so what.” Discover your unique path with an Astrovision report—your personal ‘user manual’ delivered in our celebrated podcast format.