Lunar
Return

Your lunar return comes each time the Moon arrives back at its birth longitude on the ecliptic. The Moon goes round the zodiac in about 27⅓ days, so the return comes 13 or 14 times a year, and the chart for each one is read for the weeks until the next.

Lunar returns stand beside solar ones in the older literature. Jean-Baptiste Morin wrote his rules in Book 23 of the Astrologia Gallica (1661) for “the figure of the revolution, whether solar or lunar”, in James Herschel Holden's translation: the more a revolution resembles the birth chart, the more fully it brings out what the birth chart promises. A modern book-length treatment is John Townley's Lunar Returns (Llewellyn, 2003).

In use, the lunar return sits inside the solar return the way a month sits inside a year. Astrologers read its Ascendant and the house the Moon falls in for the tone and focus of the month, note planets on its angles, and check it against the birth chart and the current solar return. Because the chart comes round so often, it is also the easiest return to test against your own records.

Here is what happens when you press the button. Ephemeris files, time zone rules and orbs are common to all our tools and explained on the methodology page.

1. Birth Moon. Your clock time of birth becomes Universal Time through the IANA zone database, and the Moon's apparent geocentric longitude at that instant comes from the Swiss Ephemeris at full precision. (Rounding it to four decimals, as a chart's planet list does, could move the return by up to about a third of a second.)
2. Start of the search. The date you enter is read as a calendar day where the chart is cast: the search starts at 00:00 that day, local time, converted to Universal Time.
3. The return. swe_mooncross_ut, the Swiss Ephemeris function built for this job, walks forward from that start to the first instant the Moon's longitude matches the birth value, converging to well under a millisecond. Called again, it yields the neighboring returns.
4. The chart. That instant, to the whole second, is cast for your birthplace or for a city you pick, with the true Ascendant and Midheaven. Houses can be Whole Sign, as preset, or Placidus or Equal. North or south of roughly 66.5° Placidus cannot be drawn, so the result switches to Whole Sign and tells you so.
5. Clock times. Each instant appears twice: in UTC, and on the wall clock of the chart's city with that date's offset, so a summer return reads in daylight time.
6. Nodal returns. The mean node's return is found by bisection near each 18.6-year mark; the true node is then scanned a quarter-day at a time for 150 days either side, with every crossing bisected.

Which return a date gives

Reading the date in local time matters for returns that fall late in the evening west of Greenwich or early in the morning east of it. One of Steve Jobs's returns came at 8:43 PM Pacific time on July 31, 1980, which was already 3:43 AM UTC on August 1, 1980. Enter August 1, 1980 for San Francisco and the calculator starts at midnight Pacific time (7:00 AM UTC), so it returns the next one, at 4:37 AM PDT on August 28, 1980, and lists the Jul 31 return as the previous one. A search starting at midnight UTC would have handed back a return that, by the local calendar, happened the evening before the chosen date.

As a check, the generator script recomputed all 13 returns in the worked example below in two independent ways, with swe_mooncross_ut and with its own bisection on the Moon's position. Neither differs from the API by more than 0.0038 seconds.

Over 1900 to 2050, for twelve sample birth positions, the 24,224 intervals between successive returns averaged 27 days, 7 hours and 43 minutes, the tropical month. Single intervals ran from 27 days 5.3 hours to 27 days 11.6 hours. The spread comes from the Moon's changing speed: it moved between 11.76° and 15.39° a day over the period, fastest near perigee, slowest near apogee.

The interval also explains why consecutive charts look so different. A return comes 27 days and about 8 hours after the one before, so it falls about 8 hours later in the day each month, and the sky stands about 143° further round than at the last one. The return Ascendant therefore jumps four or five signs from one month to the next. Meanwhile the Sun moves on about 27° each month, so the Moon's phase at the return slides backward through the whole cycle in a year: a return near a new moon is followed, about seven months later, by one near a full moon.

A calendar year holds 13 returns or 14. In the same sample 63% of years had 13 and 37% had 14, close to the 0.37 you would expect from 365.2425 ÷ 27.3216 = 13.368 returns a year.

Steve Jobs's birth certificate gives 7:15 PM, February 24, 1955, San Francisco, or 3:15 AM UTC on February 25, 1955. His Moon stood at 7°44′ Aries (7.74733° of longitude), 32° ahead of a Sun at 5°44′ Pisces. Entering his 25th birthday, February 24, 1980, as the return date for San Francisco gives the first return after it, his 335th since birth:

The return came at 4:52 AM on March 17, 1980, three weeks after the date entered, because the previous one had fallen on February 18, 1980. With Aquarius rising, the Moon lands in the 3rd house of the Whole Sign chart, which a reader would take as a month of errands, messages and the local circle; 27°05′ Pisces puts the Sun in the 2nd. The Moon was 10.7° past the Sun, so this month opened just after a new moon. None of the ten planets came within 5° of an angle. This illustrates the method; it says nothing about what his month held.

A year of returns

Following each result's “next return” gives the year. Between his 25th and 26th birthdays there were 13 returns, all cast for San Francisco:

The rising sign changed every month and the Moon visited 7 different houses. The Moon's lead over the Sun fell by about 27° a month, from just past a new moon in March to just past a full moon in September. The clock label switches between PST and PDT as daylight saving starts and ends; the Universal Time behind each return is unaffected. A birth time 4 minutes later would move his birth Moon by 2.4 arcminutes and each return by about 4 minutes, turning the Ascendant about 1.3°: the Moon was moving 14.18° a day at his birth and 15.24° at the first return.

The Moon's nodes, where its orbit crosses the ecliptic, slide backward round the zodiac once every 18.6 years. When they come back to their birth positions, astrologers speak of a nodal return, near ages 18.6, 37.2 and 55.8, and read it as a time when the themes of the natal nodes come up again (the North Node calculator covers those). The calculator lists your nodal returns with the lunar return, using two versions of the node:

• The mean node moves backward at a steady rate and crosses its birth longitude exactly once per cycle.
• The true node, the one this site's birth charts show, wobbles about the mean node with the Sun's pull on the lunar orbit. Its crossings fall within weeks of the mean node's, and when a wobble straddles the birth degree it crosses three times.

For Steve Jobs, with the true node at 3°24′ Capricorn and the mean node at 2°30′ Capricorn at birth:

Each of his true-node returns came weeks before the mean one, by between 11.2 and 40.4 days. Across 3,000 random births from 1900 to 2000, the true node crossed its birth degree once at the first nodal return in 96.1% of cases and three times in 3.8%, and no crossing fell more than 66 days from the mean node's. Which date to use is a choice between two definitions, so the calculator gives both.

The notes follow the usual modern reading of a lunar return: the rising sign gives the month its pace and mood, and the Moon's house shows where attention goes. They are interpretation, written as tendencies for a few weeks; your calculator result carries the complete entry.

The return Ascendant, sign by sign

The return Moon, house by house

• Morin de Villefranche, Revolutions: Book 23 of his Astrologia Gallica, first printed in 1661, translated into English by James Herschel Holden and published by the American Federation of Astrologers. Its laws cover lunar revolutions as well as solar ones.
• John Townley, Lunar Returns (Llewellyn Publications, 2003), a modern handbook of the monthly return.
• Astrodienst, Swiss Ephemeris programmer's documentation, for the Moon's crossing routine (swe_mooncross_ut), the house routine, and the mean and true lunar nodes.
• Our methodology page: which ephemeris files are deployed (their range is 1800–2399), how time zones are resolved, and the aspect orbs.