Earth-Centered Swirlings

Mars continues its high season of observability, indeed is still coming slightly nearer than it was at opposition a few days ago, as well as being free of the Full Moon’s glare.

This will look to you like an unfamiliar way of showing the travels of Mars in space:

Mars geocentric sphere

That’s because it is geocentric.  The Earth, instead of the Sun, is held still.  Here is the more familiar heliocentric, or Sun-centered, picture, more or less as shown in the Mars section of Astronomical Calendar 2016.

Mars heliocentric sphere

(I hope these pictures now show for you at good size.  For me, it means right-click. “view image”, click.)

In both pictures, Mars’s course is in red for 2016, yellow for 2017.  Grid lines at intervals of 1 astronomical unit (Sun-Earth distance) serve to indicate the ecliptic plane.  The zodiacal constellations, drawn on an imaginary sphere, serve to show directions out into the universe.  The dashed line is along the view from Earth to Mars at opposition, 2016 May 22.

2016 is an opposition year, in which Mars comes closest to us; 2017 is the contrasting kind of year, in which Mars is mostly far from us beyond the Sun.  Maybe I could start calling them “red years” and “yellow years.”

I wish I could make an animation, so as to show you the lively difference between these two ways of representing the Mars-track, as when I superimpose these two pictures on my screen and flip between them.  Well, here is the next best, the two in one picture.

Mars sphere heliocentric AND geocentric

The heliocentric representation is the true one, right?

Primitive mankind assumed that Earth lies still and the things in the sky move, but now we’re scientific and we know that both Earth and Mars move around the Sun.

Yes, we know it because we’ve been taught it, but it’s not what we experience with our senses.  To live is to witness the Sun taking its course across our sky.  To live and look up is to see the Moon, stars, and planets taking their courses across our sky in their curiously different manners.  To see Mars is to see it now near, now far, in curiously looping motion.

There is a school of thought that would bring back some of our respect for the older, more instinctual way of looking at the world.

Goethe, whose status in German literature is like Shakespeare’s in English, was not only poet, novelist, and civil servant but an independent scientific thinker, brilliant though outside the professional stream.  His philosophy of science was what was later called PhänomenologiePhenomena (from Greek phainein, “to show”) are the things that “are shown,” that “appear.”

Rudolf Steiner. who lived about a century later than Goethe, developed a spiritual system that he called anthroposophy, and he based the scientific part of it on Goethe’s phenomenology.  The Goetheanum, designed by Steiner as the center for his anthroposophical movement, is a mountain-shaped building at Dornach near Basel in Switzerland.  I may have a drawing of it among those I can’t at present find, because I once worked briefly as a stagehand (Kulissenschieber, “scenery-shover”) in its immense theater.  I had been invited by a gentle Dane whom I had met at another kind of theater, an ancient one, in Athens; he was a teacher in one of the Waldorf schools, which use Steiner’s system of education.

There is one of these Waldorf schools at King’s Langley, near where my parents used to live in England, and it was there, if I remember rightly, that Norman Davidson taught before he moved to New York.  He is the author of Astronomy and the Imagination and Sky Phenomena: a Guide to Naked-Eye Observation.  When he saw my Astronomical Companion, he gently criticized my division of astronomy (in the opening pages) into the Apparent and the Real.  He preferred less biased terms such as Earth-oriented vs. Space-oriented.  I considered bowing to him.  But such terms aren’t so clear.  And a phenomenologist need not object to “The Apparent.”  And “The Real” could be, for anybody, a depth we push toward and may never arrive at.

I don’t think this school of thought denies the physical reality of the Earth’s motion around the Sun; but it feels that what we sense is another kind of reality.

Once, Sky & Telescope got me to write a review of a book called Movement and Rhythm of the Stars, by Joachim Schultz.  He had been astronomer at the Goetheanum, therefore a disciple of Goethe and Steiner.  One of the strands in Schultz’s book was alternative, often delightfully intricate, ways of plotting movements, especially these patterns traced by planets in relation to the Earth.  This set me figuring how to make geocentric plots myself.  I used them alongside my usual heliocentric sphere-diagrams in Astronomical Calendars 1988 and 1989, before deciding they used too much space.  I may try some more of the kind here.



11 thoughts on “Earth-Centered Swirlings”

  1. Thanks for this posting and for your enlightening remarks as to your history with the Goetheanum, Norman Davidson and so on. I used to teach Celestial Navigation and pointed out that practical astronomy in this respect was geocentric/topocentric – that even our planetarium projector (Spitz SC2 circa 1959) was geocentric – the little light bulb inside the black dodecahedron illuminated the dome from the center-of-the-earth. Next to that was a Perspex sphere with opaque landmasses on it – so that the shadows of the surface features could be projected too – and so on. On that projector one had to climb up every day to alter positions/phases/brightness/color by hand and so developed an intimate feeling for the breathing of the planets in our sky. At that time I promulgated the Tycho Brahe system as being a good hybrid of the Experience and the “Truth”. Some time in the mid 1980s an article on the motion of the Sun around the system barycenter got dropped on my desk which was the system I felt was most natural even as a High School Freshman.
    I do remember your plots of geocentric Venus/Mercury and Mars in 1988 (pages 41 and 44 respectively) and DO CONFESS to looking for such to appear again ever since.
    Around that time I got to know and become very close to Norman Davidson – and I appreciate your memory of him – and have sent this post to his widow. Thanks again.

    1. That is highly interesting. So many relations, including to the dodecahedron of my earlier posts. I hope I will in the future be able to search back through all blog comments if I want to find, for instance, something that was said about Tycho Brahe.
      I should think that to make a planetarium machine that is heliocentric, or on Brahe’s system or anything that is not geocentric would be – well, to quote Don Quixote: “I do not say that it is impossible, but I regard it as difficult.”

    2. I meant also to say: Your words suggested to me that “the Experienced” might be an alternative for “the Apparent”. A term on the same level for “the Real” might be “the Induced”. But I’m not sure the lines are clear. When we see Mars, its brightness and size and position in relation to stars and sun and horizon are apparent to us, but its distance? – hardly.

  2. I appreciate the nod to geocentrism and its sensibility and “makes sense” to observers without instrumentation and “only” experience to guide them. I first understood it in Dorothy L. Sayers’ notes to Dante’s Commedia in which her footnotes are a classical education. “Sunrise” is so much more experiential/phanomenoligcal than “the seeming western angular elevation over the horizon due to the planet’s clockwise (eastern) rotation on its axis as it orbits the sun.” Both are accurate descriptions. One, however, I experience, the other is rather propositional and abstract.

    1. I agree, though to lie in a sleeping-bag and watch for the sun to come up through the desert horizon can give a strong sensation of being tipped eastward.

  3. Thanks Guy. I’m a skywatcher first and an amateur of astronomy by extension. I enjoy the sort of mental “binocular vision” that comes from relating the apparently geocentric sky with newer, scientifically derived models of the cosmos. Late last night the waning gibbous Moon woke me, and I went out in the back yard with binoculars. Looking at the Andromeda nebula and thinking about the Andromeda galaxy was delicious. Mars and Saturn had set too low to the southwestern horizon (or my location on the Earth had turned too far away from their lines of sight) to make it worthwhile to bring out the little telescope.

    Your geocentric orbit diagrams are quite interesting, thank you. I’ve seen similar diagrams of the long-term geocentric orbit of Venus, lovely five-petaled roses.

    Recently I bought an inexpensive sextant and I’ve been reading about celestial navigation. The authors are all very clear that celestial navigation is geocentric. “We’re navigators, not astronomers” is a typical refrain. Letting go of Right Ascension and getting my head around the Greenwich Hour Angle has been a chore. GHA is completely ass backwards from RA.

    By the way, if anybody knows where I can get an inexpensive working astrolabe for my latitude, I would be most grateful. I’ve only found expensive curiosities online.

    1. There was an article about astrolabes in a recent Sky & Telescope, possibly February, and I think the author said he got a good plastic inexpensive one from Germany.

      1. That February 2016 Sky and Telescope article got me interested in astrolabes, and led to the sextant, and the vexing Greenwich Hour Angle (which would be slightly less vexing for you in your new home). The inexpensive plastic astrolabe was made by James E. Madison of Delaware, who died recently. The German (Swiss, I think) one was brass and quite expensive. In any event, the craftsman recently retired. We need a new generation of antiquarians.

  4. Great post (as usual). Your creative in looking at things from different perspectives is good exercise for my brain.

    I used to be able to click on the pictures and they’d enlarge. That hasn’t worked for the past month or so. Right clicking doesn’t do anything either.

    So now I magnify the pictures the usual way, wherein I hit command and the plus key. I usually do this 4 or 5 times to get the image to fill my monitor.

    At least that’s how my I-Mac works.

    1. Thank you, that’s good information. Magnifying the screen display is a last resort; there are various ways to do it (e.g. for me holding the control key down and rolling the mouse wheel forward); but I don’t want to have to spell too much of this out. And I’m afraid magnifying the image makes it blurry, without the incraased resolution it should have.
      Wordpress, unfortunately, seems to keep changing the rules.

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