Astrology 101: Planetary Orbital Periods

Astrology and Astronomy are two very different trees that sprout upward from the same conceptual seed (photo by Navaneeth Unnikrishnan)...
Astrology and Astronomy are two very different trees that sprout upward from the same conceptual seed (photo by Navaneeth Unnikrishnan)…

As any astronomer will tell you, Astronomy and Astrology are not interchangeable concepts.

Astronomy is the study of the physical universe on the celestial scale – it deals with space, and all of the bits of matter that populate it.

Astrology, to contrast the two, takes the stuff of Astronomy, and uses it as a means of perceiving the ebb and flow of probabilities and events here on Earth.

Astronomy says, “The planets and stars and galaxies are this, and they do that…”

Astrology says, “Because the Planets and Stars and Galaxies are this and do that, then down here on Earth, we can expect that we will experience the following…”

The two fields of study are ultimately different in their substances, and very different in their approaches, but in many ways, they emerge from the same points of origin. They both use scientific data about heavenly bodies as their conceptual launching pads.

The skyways above us are a study in perpetual change...
The skyways above us are a study in perpetual change…

With that being the case, the budding astrologer would do well to take in plenty of scientific facts about things like the Planets, the constellations of the Zodiac, Asteroids, Planetoids, gravity, drift…and one area that may often slip through the cracks of conscious astrological analysis – especially for newcomers to the field – is the diverse set of speeds at which the Planets of our solar system revolve around the Sun. When it comes to orbital time periods, the Planets are a bit like snowflakes or fingerprints: no two of them are alike. They all travel at different velocities, and this has massive effect on the creation and interpretation of astrological charts.

It most likely won’t be a requirement even for the seriously practicing, professional astrologer to have to regurgitate orbital statistics for their clients on a daily basis, but it should always be helpful to at least have the broad strokes of the overall concept within reach. It’s the varying speeds of the traveling Planets that give rise to the ever-changing nature of our astrological charts. Each chart is like a snapshot of the sky above us, capturing a given moment – and just as snapshots of the tapestry of clouds overhead or of the array of waves breaking on a shore will always change from one moment to the next, so, too, will the split-second portraits of our solar system’s planetary dance morph and flow and evolve.

A glance at the varying orbital times of Sol’s Planets in tabular form may help to bring home this principle (I rounded off all figures to the nearest whole number for easy digestion):


Period of Revolution


88 days


225 days


365 days


687 days


12 years


29 years


50 years


84 years


165 years


248 years

Study of the observable Universe is as beneficial to the astrologer as it is to the astronomer, and considerations of perspective yield much illumination...
Study of the observable Universe is as beneficial to the astrologer as it is to the astronomer, and considerations of perspective yield much illumination…

Comparing the blunt facts like this, it starts to become clear that some of the inner Planets are like cosmic rabbits, racing around the Sun, while those farther out are more like proverbial tortoises. Since Astrology is concerned with the geometric relationships (“Aspects”) that Planets make with each other in a chart, the above table illustrates how such relationships are constantly in flux from one instant to the next.

Consider the fact that in the course of the single year it takes our own Earth to make a circuit of the Sun, speedy little Mercury encircles our star more than four times.

Then again, we manage 12 trips around the orbital track before Jupiter logs one full lap. That makes Jupiter seem leaden and plodding by comparison…

But wait! Jupiter will cruise along that same circular pathway seven times before eccentric Uranus makes it back to its own starting point even once. Jupiter suddenly seems almost peppy in this context!

And turning the focus even wider, Uranus – which seemed glacially-paced just a moment ago – will have finished nearly two full circles before dreamy Neptune completes one. Proud of this accomplishment, Uranus can almost add a third trip into the record books before far distant Pluto gets back around to its own starting point just a single time.

"As above, so below..."
“As above, so below…”

These comparatively slow orbital speeds are the reason that astrologers often refer to the Outer Planets as “generational” – a human lifetime that covers an entire Uranian orbital period (84 years) would rank as a pretty respectable showing of longevity, while no human ever conceived could claim a lifespan that would rank up there with the duration of a Neptunian or a Plutonian orbital period. In other words, entire generations will find the Outer Planets occupying essentially the same positions in their charts. To us, these Planets move at a temporal crawl, while to the Planets themselves, our human lives flash by like the blinks of a trillion tiny eyes…

It’s all relative, of course – a matter of perspective. And that’s one of the core principles of Astrology: existence occurs at infinite levels, all the time, and what happens on one is reflected on the others. Study one, and you’ll better understand the rest.

5 thoughts on “Astrology 101: Planetary Orbital Periods

  1. This is great, I’ve recently written something about orbit times for a manual I’m writing. Found this interesting, thanks!

    1. Thanks for commenting, Cheryl! Is your manual something that will be accessible to the public? I’d be curious to see what your piece is like, after having just written this post on the same topic…

      1. Hi again! It’s for a tarot workshop. At the moment it’s not in the public domain, but I’ll let you know if it’s ever “out there” 🙂

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