How Common Is Your Sun and Moon Combination? All 144 Pairings Measured

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The short answer: the figures here are shares of modelled sky-time, not shares of people or births. They say how long the Sun and Moon spent in each sign pairing over 140 years of calculated positions. On that measure every one of the 144 combinations is common: each took between 0.66% and 0.73% of the time, close to the even share of 0.69%, or roughly two and a half days a year. No single pairing can fairly be called the rarest or the most common. The lowest values form a group of 27 pairings, all with the Sun in Scorpio, Sagittarius, Capricorn, Aquarius or Pisces, and the highest a group of 52, all with the Sun between Aries and Libra.

The results in brief:

• The full spread is small. The lowest single value was Capricorn Sun with Capricorn Moon at 0.657% of the time, the highest Cancer Sun with Libra Moon at 0.732%.
• Those two endpoints are not stable winners. Measured decade by decade, many other pairings fall within ordinary variation of each end, so the answer is given as two bands, not as one pair.
• The Sun's season length does most of the work. Sun-sign seasons run from about 29.4 to 31.5 days, and the Moon's share within any one Sun season varies far less than that.
• The Moon sign on its own is almost perfectly even: each of the twelve took between 8.32% and 8.35% of the time.
• Without a birth time, the combination changed during the day on 45.7% of London dates.

Calculator note: the free birth chart gives your Sun sign and Moon sign, and with an unknown birth time it flags a Moon that may have changed sign during the date. It does not calculate how often a combination occurs, and it does not flag a Sun sign change on the birth date. Ask the Astrologist does not compute these base rates either.

What "common" means on this page

Here a combination is common or uncommon only in one strict sense: how much of the measured time the Sun and Moon spent in that pair of signs. It is not a statement about how many people have the combination. Births are not spread evenly through the year, the month or the day, and the site has no birth records, so time in the sky cannot be turned into a share of people. A pairing with a slightly smaller share of time is not scarce, special, stronger or more meaningful, and the descriptions on the individual combination pages do not depend on these numbers.

How the pairings were measured

The figures come from a single offline calculation with the routines behind the free chart, code version ac25d63. The window is the same set of 1,680 complete Sun-sign seasons measured for which zodiac sign is the rarest: twelve signs, each entered once per year from 1920 through 2059, with one extra calculated Sun change in January 2060 used only to close the final Capricorn season. That gives exactly 140 complete seasons for every Sun sign.

Each season was cut at every point where the full-precision Moon crossed into a new sign, and the elapsed time of every piece was credited to its Sun sign and Moon sign. A cell in the table below is that pairing's total time divided by the time of the whole window. Nothing was sampled at fixed clock times for the main result, and houses, angles, the Nodes, Chiron and the other planets play no part. Positions after publication are computed, not forecast.

All 144 pairings

Rows are Sun signs, columns Moon signs. Each cell is the percentage of all measured time. The final column is the Sun-sign total, the Sun's share of the window; it matches the season shares on the rarest-sign page exactly, because it comes from the same Sun sign changes. The bottom row is each Moon sign's total.

Cells are shown to three decimals so that pairs can be told apart, but differences in the third decimal are smaller than the decade-to-decade variation described below. The even share is 100% ÷ 144 = 0.694%.

Two effects multiplied together

Any cell can be split exactly into two parts:

pair share = the Sun sign's share of time × the Moon sign's share within that Sun sign's time

The first part is the season-length effect already measured for the Sun alone. Because Earth moves fastest in early January and slowest in early July, the Sun crosses Capricorn in about 29.4 days and Cancer in about 31.5. Rows with Sun in Scorpio to Pisces therefore start from a smaller total (8.06% to 8.20%), and rows with Sun in Gemini to Leo from a larger one (8.57% to 8.61%).

The second part is the Sun-Moon geometry within a season. Inside every Sun row, each Moon sign took between 8.15% and 8.52% of that row's time. That range is narrower than the range between rows, which is why the low band below is made up of late-year Sun signs and the high band of spring and summer ones. Within-row patterns are covered in sign-offset terms on how often the Moon is in your Sun sign.

Why there is no single rarest pair

A full-window minimum can be an accident of where the 140 years happen to start and stop. To test that, the rule was fixed before any results were seen. The window was divided into fourteen ten-year blocks (1920 to 1929 up to 2050 to 2059), each holding ten complete seasons of every Sun sign, and every pairing's share was measured in each block. The standard deviation of those fourteen block shares shows how much a cell moves from decade to decade; across the 144 cells it ran from about 0.011 to 0.029 percentage points.

A pairing joins the least-common band if its full-window share is no further above the minimum than the larger of the two cells' standard deviations. The most-common band uses the same rule from the maximum downwards. One pair would be named outright only if no other cell qualified. This is a stability rule of thumb, not a confidence interval or a significance test.

Least-common band: 27 pairings

Most-common band: 52 pairings

The remaining 65 pairings sit between the two bands. Taken together, the honest answer to "which combination is rarest" is: a group of late-year Sun signs with a range of Moon signs, all within about three hundredths of a percentage point of each other, and all still holding close to one 144th of the time.

When the birth time is unknown

The combination can change during a single calendar date. Every London date from 1 January 1920 through 31 December 2059 (51,135 dates) was followed from 00:00 to the next midnight, with the 23-hour and 25-hour clock-change days kept as they are, and cut at every Sun and Moon sign change inside it.

• On 23,388 dates (45.7%) the date held more than one combination. The Moon changed sign on 22,459 of them, the Sun on 1,680.
• On 751 dates both changed, so three combinations occurred in one day: the starting pair, a middle pair, and an end pair. Looking only at the first and last minute of such a date shows two of the three and misses the middle one.

With an unknown time, the free chart helps with the Moon half of this. Its check is explained on Moon sign without a birth time. It does not list the full set of possible combinations, and on a date when the Sun changes sign, the Sun sign itself depends on the birth time; born on the cusp covers that side. In both cases more than one combination is possible for that date.

Near a sign change, the measured timings also have limits. The Moon's sign changes agree with an independent offline reference, the Swiss Ephemeris, to within about a minute and a half, while for the Sun the margin is about 20 minutes. A birth inside those margins is too close to call.

A cross-check from noon charts

As a separate and coarser check, the free chart's routines were also run for London at 12:00 local clock time on all 51,135 dates, and each noon chart was counted under its Sun-Moon pair. The noon counts ranged from 335 to 377 dates per pair, against an even 355. They follow the exact time shares closely (a rank correlation of 0.93 across the 144 cells); the lowest noon count falls inside the least-common band above and the highest inside the most-common band, and 22 of the 27 lowest noon pairs are also in the exact least-common band. Because each date is assigned to one moment, the noon count is only a cross-check, and the exact time shares are the answer on this page.

Reading the result sensibly

These are frequencies of a pattern in the sky. A combination in the least-common band is not rare in any sense a reader would notice, and one in the most-common band is not ordinary in meaning. Nothing on this page describes personality, emotional needs, compatibility, health, money or future events, and none of it says how many people share your combination. For what the pairings are usually taken to describe, start from the Sun and Moon combinations hub.

Related articles

• How Often Is the Moon in the Same Sign as Your Sun?
• Which Zodiac Sign Is the Rarest? Measured by Sun-Sign Season Length
• Born on the Cusp? Why Zodiac Sign Dates Shift From Year to Year
• Can You Know Your Moon Sign Without a Birth Time?
• Sun, Moon and Rising Explained
• Sun and Moon Sign Combinations