Astra For Me THE SKY, THIS MONTH
RETROGRADE  ·  THE PART THAT IS US

Pluto spends four months in ten going backwards

We counted, day by day, across 150 years. Pluto is retrograde 43.8% of the time, Neptune 43.2%, Uranus 41.0%, and the figure keeps climbing with distance towards one half. That is not something the planets are doing. It is us.

Astra For Me 27 Sep 2026 11 MINUTE READ
MEASURED

Anything in a violet panel we computed from DE421 ephemeris data. You can check it.

INTERPRETED

Anything on a gold rule was said by people, at a particular time. We say who, and when.

Nothing out there is reversing

SAY THIS PART FIRST

A planet said to be retrograde has not slowed down, stopped and turned round. Its orbit does not do that and could not. What has changed is the line between us and it, because we are moving too, on a smaller and faster orbit, and for part of each cycle we sweep past it.

That is the entire phenomenon. It happens to every planet, and how often it happens to each one turns out to be a clean measurement.

HOW OFTEN EACH BODY GOES BACKWARDS
BodyDistance from the Sun, AURetrogradeDays per runDegrees backed up
Mercury0.4019.22213.3
Venus0.727.24216.0
Mars1.539.67416.4
Jupiter5.2030.21209.9
Saturn9.5636.51386.8
Uranus19.2941.01524.0
Neptune30.0943.21582.8
Pluto36.3843.81602.5

Sampled every day from 1 Jan 1901 to 1 Jan 2051, using the same day-to-day motion the app itself uses to decide whether a planet is retrograde today. Percentages are of all days.

Read that table from Mars downwards and the trend is exact. Every body further out is retrograde more often than the one inside it, with no exception across the 6 bodies outside our own orbit: Mars at 9.6%, then 30.2, 36.5, 41.0, 43.2 and 43.8.

Why the trend goes where it goes

AND WHAT IT IS HEADING FOR

The further away something is, the less it moves against the sky under its own steam, because a wider orbit is also a slower one. Push that to the limit and you have a body that hardly moves at all, whose apparent position is nothing but the reflection of our own trip around the Sun.

Something that only reflects our motion swings one way for half the year and the other way for the other half. So the fraction should climb towards a half and never reach it, and our furthest body sits 6.2 percentage points short of that.

The last column of the table is the check on this, and it is the part that surprises people. The time spent going backwards goes up with distance; the distance covered while going backwards goes down. Mars backs up 16.4° in a run, Pluto 2.5°. A body at the limit would be retrograde half its life and would barely move while it was.

THE OUTER PLANETS BARELY MOVE AT ALL
Days Pluto stands still24.0% of them
Days Mars does0.4%
Days Mercury does0.3%
Standing still meansunder 0.01° in a day

A threshold, not a fact about the sky, so we state it. At that definition Pluto is effectively stationary for most of a year in four, which is why a chart's outer planets so often sit at a station.

The time spent going backwards rises with distance. The ground covered while doing it falls. A very distant body would be retrograde half its life and barely move at all.

The two that break the rule

AND THEY BREAK IT FOR A DIFFERENT REASON

Across all eight bodies the trend fails, and it fails at the very first step. Mercury is the nearest of them and is retrograde 19.2% of the time, which is 2.6 times as often as Venus, further away at 7.2%.

That is not a flaw in the reasoning; it is a different mechanism wearing the same name. Mercury and Venus orbit inside us and move faster than we do, so their backward stretches happen when they swing between us and the Sun and overtake us. For everything outside our orbit we do the overtaking. Same appearance, opposite cause, and the two obey different arithmetic.

One more thing about that table, because it is the trap we walked into first. Its distance column is distance from the Sun, which is what the reasoning is about: a wider orbit is a slower one. Measured from the Earth instead, Mercury and Venus average 1.04 and 1.14 AU, which makes them look like near neighbours sitting a little inside Mars. From the Sun they are 0.40 and 0.72, and Venus is nearly twice as far out as Mercury. A mean taken from a moving vantage point does not reverse them, it flattens them, and it flattens exactly the spread the argument is about. From Mars outward the two measures agree to within a few per cent, which is why nothing else here depended on the choice.

We checked the trend rather than assuming it, and reported both answers, because a rule stated without its exception is the tidier sentence and the wrong one.

What that means for a chart

THE AWKWARD ARITHMETIC

If Pluto is retrograde 43.8% of the time then roughly 4 people in ten have it retrograde at birth. The same goes, near enough, for Neptune and Uranus.

HOW MANY OF THE EIGHT ARE RETROGRADE AT ONCE
How manyDaysPercent
044988.2
11110020.3
21565128.6
31353724.7
4722313.2
523004.2
64660.9
7120.0

Counted across every day of the span. The average is 2.3 of the eight, the most ever 7, and only 8.2% of days have none at all.

So a chart with something retrograde in it is not unusual; a chart without is. That is an uncomfortable number for a reading that treats an outer-planet retrograde as a personal signal, and it is worth stating rather than leaving for someone else to notice.

The response inside astrology, where the point is acknowledged at all, is to treat the outer planets' retrogrades as generational rather than individual, and to let house and aspect do the work of telling one person from another. We are reporting that response, not endorsing it. The base-rate objection is a standing one in the academic literature critical of astrology, and it is not answered by a percentage.

Thirteen centuries of getting it right for the wrong reason

THE INTERPRETATION, AND ITS HISTORY

From here down we are reporting rather than measuring.

THE GREEK WORLD, 3RD CENTURY BC TO 2ND CENTURY AD

Retrograde motion was the central problem of Greek astronomy, and it was solved: not explained, but predicted, accurately, for more than a thousand years. The device was the epicycle, a small circle carried round on a larger one, and the credit is shared. The geometry is generally attributed to Apollonius of Perga, who proved that an epicycle and an off-centre circle can produce the same appearances; Hipparchus put it to quantitative use; Ptolemy assembled the full predictive system in the Almagest and added a further device, the equant, to make the timings come out right.

It is a mistake to call this a mystery that waited for Copernicus. It was a solved computational problem resting on a false picture, which is a different and more interesting thing.

The programme is usually summed up in a phrase, saving the appearances, and traditionally credited to Plato. Be careful with that: it reaches us only through Simplicius, writing about nine hundred years later, quoting a chain of books that no longer exist.

FRAUENBURG, 1543

Copernicus's argument in De revolutionibus is the one this article has been measuring. Put the Sun at the centre and retrograde motion stops needing a mechanism: it is what you see when a faster inner body passes a slower outer one, and it follows from the arrangement rather than being added to it.

It also explains something Ptolemy had to stipulate separately for every planet, namely why each one turns retrograde when it does relative to the Sun. One fact about the Earth replaced a rule per planet. Historians generally rate this among his strongest arguments, and it is an argument from unification rather than from simplicity.

Which matters, because the popular version of this story is wrong in a specific way. Copernicus did not abolish epicycles. He removed the need for one to produce retrograde motion, and then kept epicycles for other purposes, notably to get rid of Ptolemy's equant, which he objected to on principle. His finished system used about as many circles as the one it replaced.

ON CALLING A RETROGRADE PLANET WEAK

The astrological reading of retrograde as a weakened condition is old but not as old as it is usually said to be, and it is not Ptolemy's word.

What the Tetrabiblos actually offers is a scale of speed and position relative to the Sun: planets are strongest when they rise before it and are gaining in their own motion, and weaker when they set after it and are slowing down. That is a continuum about velocity, not a verdict on being retrograde, and the word debilitated is not in it.

The formal doctrine, in which retrograde motion is one item on a list of accidental debilities scored against a planet, is a medieval construction, elaborated in the Arabic tradition and given its classic English statement by William Lilly in Christian Astrology in 1647. If you have met the idea, that is the lineage it came down.

What we do with it

OUR OWN POSITION, DECLARED

This app marks a planet retrograde when its own motion over a day is backwards, which is the definition every figure above was counted with. It does not score a planet as debilitated for being retrograde, because that is a specific doctrine with a specific history rather than a fact about the sky.

What the sky supports is everything above the gold rule: the fractions, the trend, the exception, and the reason for all three. What you do with a retrograde Pluto is a question about a tradition, and the honest thing is to tell you which of those you are being handed.

YOUR OWN SKY

Which of your planets were going backwards, and by how much. Computed free.

Compute your chart

Sources

SO YOU CAN CHECK THEM YOURSELF