Neptune Square Neptune: Is It Really Around 41?

← Back to Transits

In Neptune square Neptune, moving Neptune reaches the point 90° ahead of where natal Neptune stood when you were born. Neptune takes about 165 years to circle the zodiac, so this first, waxing square is the only Neptune square most people meet, and it is the only one measured here. The later phases of the cycle are left aside.

Astrology books usually put this square "around 41". That is a testable claim, so this page tests it. Neptune's orbit is close to a circle, which predicts a tight age band, very unlike Pluto square Pluto, where the age swings by more than twenty years with the birth year. The measurements below use the Neptune routine behind the free chart, a fixed sample of 2,184 births from 1920 to 2010, and three invented people who appear on other transit pages.

What came out:

• "Around 41" holds, within limits. The middle exact hit (defined below) came between ages 39.5 and 42.7 for every birth in the sample, with a median of 41.2. For 1,692 of the 2,184 births (77%) it fell between 40 and 42.
• One square is not one date. Every square had three exact hits (1,626 births) or five (558), never one. A three-hit square ran for about ten months, a five-hit square for about a year and seven months, so the first hit could come as early as 38.7 and the final one as late as 43.0.
• A slow drift, not a jump. Births up to the late 1970s had a median middle-hit age of about 41.2 to 41.5; births from 2000 on about 40.2 to 40.6 (five-year groups).
• The three worked examples (born 1970, 1990 and 2002) have middle hits at 39.9, 41.6 and 40.9, all within 1.7 years of each other.

Educational guide: Astrologist.com does not offer a transit calculator, transit calendar, Neptune timing tool or automated report, and the free birth chart covers the natal chart only. The dates and ages here come from a one-off offline calculation for this article using the chart's own Neptune routine, not from a feature of the site, and none is worked out for your chart. Dates after October 2026 are model projections.

Where this page sits

The qualitative reading of the slow midlife squares is on Neptune and Pluto midlife transits, and the Uranus squares have their own page. This one is narrower: it checks the familiar age against a dated sweep and explains why one Neptune square stretches over most of a year or longer.

How the numbers were made

These rules were written down before any square was solved:

• Source. Natal Neptune and moving Neptune both come from the production planetary routine of the free chart (VSOP87B via the astronomia library, apparent Tropical longitude of date), with its time handling. For every sample birth, natal Neptune was confirmed against the chart's own birth-chart output, to within its 0.01° storage step.
• Search boundary. Neptune was followed every 12 hours from 1 January 1920 to 31 December 2099 on one unwrapped longitude track. The end date is a boundary chosen for this study so that the Pluto and Neptune pages are comparable; it is not a statement about how far the site's Neptune is valid, and nothing past it was computed.
• Hits and turns. A hit is a crossing of natal Neptune + 90°, forward (F) or backward (R), solved to under a minute inside the production model. The turning points between hits were located to group them and are shown to the day.
• Grouping. One square is the connected run of crossings with a turn between each pair: F R F or F R F R F (a single F is also allowed, but never occurred). It counts as complete once Neptune has turned direct past the point. A turn that reached the point without crossing would have been listed as a touch.
• Quoted age. The middle crossing in time order: the backward hit of three, the third hit of five. First hit, final hit and span are given too.
• Sample. 12:00 UT on the 1st and 15th of every month from 1 January 1920 to 15 December 2010, 2,184 births. Age in years of 365.2425 days.

Three people, three similar ages

The births are the invented ones from Uranus square Uranus (Bristol) and Chiron return (Persons A and B), reused without reselection.

Bristol, 1970: middle hit at 39.9

12 August 1970, 14:20 BST-trial time, Bristol (13:20 UT). Natal Neptune 28°07' Scorpio; square point 28°07' Aquarius.

The next loop came remarkably close. Neptune's direct turn on 9 November 2011 stopped 51" past the point, so it did not cross back. Had it reached the point, this would have been a five-hit square. The Swiss Ephemeris also has that turn about 50" past the point.

Person A, 1990: middle hit at 41.6

14 March 1990, 08:30, Rotterdam (07:30 UT). Natal Neptune 14°16' Capricorn; square point 14°16' Aries.

All projections. The quarter from Capricorn to Aries took about 41.6 years.

Person B, 2002: middle hit at 40.9

20 January 2002, 11:05, Ghent (10:05 UT). Natal Neptune 8°09' Aquarius; square point 8°09' Taurus.

A year earlier, on 10 August 2041, Neptune turned retrograde about 2' short of the point, so the square did not start then. Again all projections.

Compare the Pluto page, where the same three births have their Pluto squares at 35.8, 44.9 and 54.1: an 18-year spread against Neptune's 1.7.

2,184 births: how tight is the band?

All 2,184 first waxing squares were complete well inside the search boundary. The 24 births in 2010 had the latest, over by 4 April 2052, closed by a direct turn on 8 February 2053. No square was censored, so the counts below are the whole sample.

So the familiar figure is a fair summary, with two corrections. First, the band is about three years wide, not a single birthday: 137 middle hits came at 39.x, 697 at 40.x, 995 at 41.x and 355 at 42.x. Second, because a square lasts most of a year or more, "at 41" is a window rather than a moment. For exactly half the sample (1,095 births) the period from first to final hit included the 41st birthday; for the rest it lay wholly before or after it.

The drift has a simple cause. Neptune's net progress per year varies only a little, from about 2.17° in Scorpio and Sagittarius to about 2.25° in Aries and Taurus. The earlier births have their square points in the slower stretch, Scorpio to Capricorn; births from the mid 1980s on have theirs in Aries or Taurus, where Neptune is a touch faster, so the quarter is covered sooner and the square comes up to about a year earlier.

By natal sign

Every sign group sits inside the same three-year band. That is the real contrast with Pluto: for Neptune the natal sign tells you very little about the square age. The extremes were a birth on 1 December 2010 (natal Neptune 26°04' Aquarius), middle hit at 39.5, and one on 1 December 1948 (14°35' Libra), at 42.7.

Why three or five hits

Neptune turns retrograde once a year for a little over five months and slips back about 2.8°. Over the year it gains only about 2.2°. So every backward stretch reaches back past the start of the previous one, by about 0.6° each year, and there is no degree that Neptune passes only once. Any square point is crossed forward, backward and forward again.

A point that falls inside the 0.6° where two consecutive loops overlap is crossed twice more: five hits. With 0.6° of overlap in roughly 2.2° of yearly progress, about a quarter of points land in an overlap, which is close to the 558 of 2,184 five-hit squares found. In the sample, three-hit squares lasted 0.82 to 0.84 years from first to final hit and five-hit squares 1.57 to 1.63 years.

No turn reached a square point without crossing, so there were no touches. 212 turns came within 3' of a sweep square point; the Swiss Ephemeris, used only as a check, put Neptune on the same side at 211. The odd one: for a birth on 1 January 1959, a retrograde turn on 8 May 2000 came 0.51" past the point in the production track, giving hits on 7 and 9 May 2000 and five hits in all, while Swiss has the same turn 0.19" short, which would leave three. The production count stands, with that flag.

Birth time

Shifting each worked birth by 12 hours either way, as decided in advance, moved natal Neptune by between 0.0006° (Bristol, where Neptune was nearly stationary) and 0.019° (Person B). Hit dates moved by under an hour for Bristol, up to about 8 hours for Person A and up to about 20 hours for Person B. All three kept three hits. A square point that sits near a turn, like Bristol's next loop, is where a different birth time or source could change the count.

Precision and the independent check

Kept separate on purpose:

• Solver tolerance. Under a minute within the production model. It says nothing about the astronomy.
• Production model. VSOP87B Neptune with the chart's apparent-place reduction.
• Repository regression tests. The project checks this Neptune against the Swiss Ephemeris at daily noon from 25 December 1919 to 8 January 2061, with a 0.05° position allowance and a station-timing allowance. Every square on this page falls inside that span. Those are allowances, not error bars.
• Observed Swiss differences, for these dates only. Swiss natal Neptune differed by at most 0.61" for the three births; Swiss Neptune sat within 2.0" of the square point at all nine worked hits; solving them again in Swiss moved them by up to about 34 minutes (24 with a Swiss natal point); every turning point fell on the same UT date. Swiss supplies no date on this page.

Reading it

Astrologers often describe the Neptune square as a time when ideals are looked at again. Treat that as an optional theme for reflection. The square does not predict events, health, relationships or finances, and an exact date marks a geometry, not a turning point in a life. The useful fact from the measurements is the shape of the timing: a window of most of a year, somewhere between about 39 and 43.

Finding your own

1. Take natal Neptune from the free birth chart as a longitude from 0° Aries and add 90°.
2. In a Tropical ephemeris, list every date Neptune reaches that point; expect three, or five if two loops overlap there.
3. Look at the turns nearest the point. A turn within a few arc-minutes is where sources can disagree.
4. Record the source and time standard, and give dates to the day. Dates from November 2026 on are projections.

The general method is in how to read transits without a transit tool. Ask the Astrologist can talk through natal Neptune or dates from your own ephemeris; it does not calculate transit dates.

Related articles

• Pluto Square Pluto (the opposite result: an age set by birth year)
• Neptune and Pluto Midlife Transits
• Uranus Opposition
• Uranus Square Uranus
• Life-Cycle Transits Overview
• Neptune Transits to Natal Sun
• Outer Planets