How Often Is the Moon in the Same Sign as Your Sun?

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The Moon goes all the way round the zodiac in about four weeks, while the Sun takes a year. So unlike Mercury or Venus, the Moon can be in any sign at all relative to the Sun: the same sign, the opposite sign, or anything in between. This page measures how the time splits between those twelve possibilities, using the same routines as the free chart. For what a Moon sign is usually taken to describe, see what your Moon sign means; here the subject is frequency alone.

The results in brief:

• The Moon was in the Sun's sign for 8.20% of the measured time, about 30 days a year, which is very close to one twelfth (8.33%).
• The opposite sign took 8.20% as well. The twelve possible positions all fell between 8.20% and 8.48%; none is common or scarce in any practical sense.
• The split hardly depends on the Sun sign. Within each Sun sign's own time the same-sign share ran from 8.15% to 8.24%, and the opposite share from 8.17% to 8.25%.
• On 45.7% of London calendar dates the Sun-Moon offset was not the same all day, nearly always because the Moon changed sign. On 751 of those dates it changed and then changed back before midnight.
• Sharing a sign is not the same as a New Moon or a conjunction. A same-sign Moon can also be up to 30° behind the Sun, which the site's phase scheme counts as Balsamic.

Every share on this page is a share of time in the sky, not a share of people or births.

Calculator note: the free birth chart shows the Sun's sign and the Moon's sign in its planet table, but it does not count how many signs apart they are. With an unknown birth time it compares the Moon's sign at the start and end of the date and lists both if they differ; it does not report the full range of Sun-Moon offsets, and on a date when the Sun changes sign it does not flag the Sun at all. Ask the Astrologist does not compute these base rates either.

Counting the offset in signs

The position is described as an offset: the number of whole signs from the Sun's sign forward to the Moon's, in zodiac order.

• 0 means the Moon is in the same sign as the Sun.
• +1 to +5 means the Moon is that many signs ahead of the Sun. Sun in Capricorn with the Moon in Gemini is +5, because Gemini comes five signs after Capricorn once the count wraps from Pisces to Aries.
• −1 to −5 means the Moon is that many signs behind. Sun in Leo with the Moon in Cancer is −1.
• +6 is the opposite sign, such as Sun in Aries with the Moon in Libra. Six ahead and six behind land on the same sign, so there is only one opposite class.

That gives twelve classes in all, one for each sign the Moon can occupy.

Same sign, conjunction and New Moon are three different things

A shared sign is a statement about two 30° slots. It is not an aspect and it is not a phase.

• Conjunction. The free chart's conjunction uses an 8° orb, which can reach across a sign line. A Sun at 28° Taurus and a Moon at 2° Gemini are conjunct but one sign apart; a Sun at 2° Taurus and a Moon at 27° Taurus share a sign but are 25° apart and not conjunct. The aspect itself is described on Sun conjunct Moon.
• Moon phase. The site's natal phase is the directed angle from the Sun forward to the Moon, divided into eight 45° sectors. A same-sign Moon ahead of the Sun is in the first 30° of the cycle, which is the New phase. A same-sign Moon behind the Sun is between 330° and 360°, which is the Balsamic phase, the last of the eight. So a same-sign chart is not automatically a New Moon chart, and it is not the astronomical New Moon either, which is the single instant when the angle is exactly 0°. The full scheme is on natal Moon phases explained, and Moon phase vs Sun-Moon aspects sets phase and aspect side by side.

Neither conjunction rates nor phase rates were measured again for this page.

How it was measured

This is one offline run of the routines behind the free chart, code version ac25d63. The measured window is the same 140 years used on which zodiac sign is the rarest: 1,680 complete Sun-sign seasons, one for each sign starting in each year from 1920 through 2059. One extra Sun change, the start of Aquarius in January 2060, was calculated only to close the last Capricorn season.

Inside that window, every moment the calculated Moon reached 0° of a sign was found and refined to well under a second, 22,459 Moon sign changes in total. Each Sun season was then cut at every Moon sign change, and the time in each piece was added to its Sun sign, Moon sign and offset. The sign boundaries come from the full-precision longitudes, not from the rounded figures the chart displays.

The result is a share of elapsed time, not a count of sample dates. Houses, angles, the Nodes, Chiron and the other planets play no part. Dates after publication are computed positions, not forecasts.

How the twelve offsets split

Over the full window the same sign and the opposite sign are the two lowest values and the classes three signs either side the two highest, but the whole spread is less than three tenths of a percentage point. Measured in separate ten-year stretches, every class moved around by a similar amount, between roughly 8.0% and 8.8%, and the order changed from decade to decade. The fair reading is that each of the twelve offsets takes close to one twelfth of the time.

The small departures from exactly 8.33% come from the orbital geometry of the Sun and Moon in this window: the Moon's speed varies along its orbit, and so does the Sun's through the year. This page does not split the result into separate causes.

By Sun sign

Each row uses only the time the Sun spent in that sign, 140 seasons per sign. The denominator is that time, not a number of charts, and it differs a little between signs because Sun-sign seasons differ in length.

Every Sun sign gives almost the same answer: the Moon spends a little over 8% of that season in the Sun's own sign and about the same in the opposite one. Because the Moon laps the zodiac roughly once a month, each Sun-sign season of about 30 days lets it pass through every sign at least once, so no Sun sign is cut off from any Moon sign. A Sun-Moon pair does not become more or less meaningful because of these figures. How often each of the 144 pairs occurs, including the effect of season length, is measured on how common your Sun and Moon combination is.

When the birth time is unknown

A single chart is one moment, and the Moon moves about 13° in a day. To see how often the offset depends on the time of birth, every London calendar date from 1 January 1920 through 31 December 2059 (51,135 dates) was followed from 00:00 up to the next midnight, including the 23-hour and 25-hour days when the clocks change. Each day was cut at every Sun and every Moon sign change inside it, and the offset was read in every piece.

• On 23,388 dates (45.7%) the offset was not constant over the day. The Moon changed sign on 22,459 dates (43.9%) and the Sun on 1,680 (3.3%).
• On 751 dates both changed sign on the same day. On every one of them the offset moved by one step and then came back to where it started, because the Moon moving on adds one sign to the count and the Sun moving on takes one away. The Sun-Moon pair itself was different at the end of the day, but the offset class at 00:00 and at midnight was the same.
• No date had three different offsets.
• On 929 dates only the Sun changed sign, so the offset changed while the Moon's sign stayed put.

Those 751 return-to-start dates are why checking only the first and last minute of the day is not enough for the offset: its endpoints match even though a different offset occurs between the two sign changes. For the Sun-Moon combination, the endpoints do differ, but they reveal only two of the three combinations that occurred that day, so a full-day check is still needed to list every possibility. The free chart's unknown-time check is built for the Moon sign alone, and the guide to a Moon sign without a birth time explains how to read it. On a date when the Sun changes sign, the Sun sign can depend on the birth time too, and the chart does not flag that. If either body is close to a sign line on your birth date and the time is unknown, treat the offset as uncertain for the whole day.

How precise the sign changes are

Three separate facts set the limits of the timings above.

1. Refinement. Each Moon sign change was located to far better than a second in the chart's own model.
2. Independent reference. Compared offline with the Swiss Ephemeris, the chart's Moon sign changes differed by a median of about 21 seconds and at most about 1.3 minutes. On 3 of the London dates this would move the change across midnight.
3. Display rounding. The chart shows longitudes to 0.01°, so the sign it displays flips about half a minute before the full-precision change.

For the Moon, a birth time within a couple of minutes of a sign change is too close to call. The Sun's sign changes need a wider margin, about 20 minutes either way, set out on born on the cusp.

Ruben as the worked example

Ruben is the fictional chart from how to find aspect patterns: London, 5 January 1993, 12:00. He was fixed as this page's example before any figure here was calculated, and his chart was recomputed with code version ac25d63.

• Offset +5. Gemini is five signs after Capricorn, a class that took 8.25% of the time the Sun spent in Capricorn.
• Not same sign, not opposite. His Moon is in neither of the two classes this page's title asks about.
• Phase. Counted forward from the Sun, his Moon is 140.56° ahead, which places him in the Gibbous phase. That is a separate measurement from the sign offset.
• Not the same all day. The Moon entered Gemini at 01:42 GMT that morning (the Swiss Ephemeris puts it about half a minute earlier). Before that it was in Taurus, offset +4. With the time entered as 12:00 the chart is unambiguous, but if his birth time were unknown, the free chart would show his Moon as uncertain, Taurus or Gemini, and the offset would be +4 or +5.

His result is ordinary, which is all it shows about him.

A second check: noon dates

As a separate, coarser check, the free chart's routines were also run for London at 12:00 local clock time on all 51,135 dates. Each noon chart was given its offset class. The noon counts came out close to the exact shares: same sign on 4,193 dates (8.20%), opposite on 4,190 (8.19%), and the classes three signs either side the most frequent at 8.49% and 8.46%. These counts are only a cross-check; the exact time shares above are the answer on this page.

Reading the base rate sensibly

How often the Moon shares your Sun's sign says how the sky spends its time, nothing more. A same-sign Moon is not doubled strength, and an opposite-sign Moon is not a built-in conflict. None of these figures describes personality, emotions, compatibility, health, money or future events, and none says how many people have a given placement.

Doing the check yourself

1. Read the Sun's sign and the Moon's sign from the planet table of the free birth chart.
2. Count forward in zodiac order from the Sun's sign to the Moon's: the same sign is 0, the next sign +1, and so on; six signs on is the opposite sign, +6; a Moon one to five signs before the Sun's sign is −1 to −5.
3. Find the share in the first table, or your Sun sign's row for the same-sign and opposite figures.
4. If you do not know your birth time, check whether the Moon or the Sun changes sign during your birth date. If either does, the offset may differ across the day, even when the start and the end agree.

Related articles

• How Common Is Your Sun and Moon Combination? All 144 Pairings Measured
• Natal Moon Phases Explained: The Sun-Moon Cycle at Your Birth
• Sun Conjunct Moon
• Can You Know Your Moon Sign Without a Birth Time?
• How Often Is Mercury in the Same Sign as Your Sun?
• What Your Moon Sign Means in Astrology
• Moon Signs