What magic? Where magic? 5c: Green stars (concluded.)

The previous post ended with the possibility that three ‘greenstars’ in the diagram on folio 67v might be green because at some stage in the material’s transmission a overseer had used a ‘greenpencil’ (so to speak), correcting what had been done by the scribe/draughtsman. We know there are no stars that appear dark green to the naked eye, and only one that is faintly ‘green-ish’ (see previous post).

Take a closer look at those green stars – and the difference between the brown outlines made by the scribe, and the green which we’re attributing instead to an overseer of the work. The difference seems to be in the number of points.

Why should it matter? There was obviously nothing perceived as unlucky about the original number of points on each. The same area of the map has others with the same numbers.

But it looks very much as if the number of points on a star – in this diagram at least – mattered enough to add that green paint/ink.

While it might be possible to create a theory that the distinctions refer to relative importance for some system of thought in which stars and colours had a part (cf correlation of stars and the patterns of geomancy in post before last).

But I’m going to test a simpler possibililty – the stars on folio 67v (not necessarily anywhere else in the manuscript) are being defined by relative magnitude.

I included (via Elly Dekker’s paper)* the following legend in my header for the post before last. It comes from a late sixteenth century Venetian sky-chart. Here’s a closer detail of the legend. The numbers which I’ve added to that detail (in green) are just the number of points given for its stars of the first three orders of magnitude, if they had been described in a descending number of points/magnitude – a system which would be clearer for anyone working to a small scale. (dropped passage – restored 31st. July.)

  • Elly Dekker, ‘Caspar Vopel’s Ventures in Sixteenth-Century Celestial Cartography’, Imago Mundi, Vol. 62, No. 2 (2010), pp. 161-190. (dropped. restored August 2nd.)

And now here’s the disposition of stars by number of points for folio 67v.

If this is the sort of work you like, you’re welcome to print of that last image above, and play with it by reference to a downloadable spreadsheet for Ptolemy’s star-magnitudes. It comes courtesy of John Pratt and includes as well the formerly standard designation by Greek letter and constellation. (Astronomers don’t use names today, just the star’s official number).  After downloading Pratt’s table, convert and save as Xcel so you can work with it.

Disposing of some guesses..

Since Canopus, Sirius and α Centauri are three of the brightest stars in the heavens – alpha Eridanus another – and the first three are found so close to one another amost making a straight line towards the southern celestial Pole, so  my first thought is that I should probably toss out that initial guess about the the sun’s ‘pointer’.  For sky map see header. The view is north-up.

N.B. – please read comments below this post for updated information. (note added 1st August 2021).

Stellar Magnitudes – not Ptolemy’s idea.

Europe didn’t invent a system of star-magnitudes, and neither did Claudius Ptolemy whose description is found in Book 8 of the Almagest.

This paragraph gives the usual story

Star magnitudes do count backward, the result of an ancient fluke that seemed like a good idea at the time. The story begins around 129 B.C., when the Greek astronomer Hipparchus produced the first well-known star catalog. Hipparchus ranked his stars in a simple way. He called the brightest ones “of the first magnitude,” simply meaning “the biggest.” Stars not so bright he called “of the second magnitude,” or second biggest. The faintest stars he could see he called “of the sixth magnitude.” Around A.D. 140 Claudius Ptolemy copied this system in his own star list. Sometimes Ptolemy added the words “greater” or “smaller” to distinguish between stars within a magnitude class. Ptolemy’s works remained the basic astronomy texts for the next 1,400 years, so everyone used the system of first to sixth magnitudes. It worked just fine.

Galileo forced the first change.

  • Alan MacRobert, ‘The Stellar Magnitude System’, Sky and Telescope, (August 1st., 2006).

Hipparchus was born in Nicea and died in Rhodes. He 190 BC-120 BC.

On the map below, in addition to those places I’ve added Constantinople and Tralles (see previous post). Part of the Cyclades can also seen on the map below – (see post of July 11, 2021. Aratus of Soli was also a native of Asia minor, roughly the latitude of Rhodes, but past the edge of this detail.

I’ve already published a fair bit my research into charts and cartes marine though voynichimagery so here I’ll say only that the system of points-for-magnitude in that sixteenth century Venetian work is unlikely to have been novel. In folio 67v, the diagram looks as if an older version of it had been copied meticulously and then updated, and the fifteenth-century scribes copied everything exactly, ‘green stars’ and all. But there’s no way to be sure about the last point.

  • Bradley E. Schaefer, ‘The Thousand Star Magnitudes in the Catalogues of Ptolemy, Al Sufi, and Tycho Are All Corrected For Atmospheric Extinction’, Journal for the History of Astronomy,Vol.44 No.1, (March 2013),

Just by the way … Marco Ponzi reproduced the following image in one of his posts (Viridis Green). I mention it only because it uses the word ‘magnitudes’. Readers should apply to him for more information, and if re-using it credit him with finding and bringing it to notice.

I’ll say more on the general subject of colour and pigments next time.

Meanwhile, I leave you with this thought from John Gage:

:..in spite of a widespread belief in the universality of certain colour ideas, [colour] is, like all formal characteristics, ideologically neutral It can be seen to have served a very wide range of aesthetic and symbolic purposes; and the same colours, or combinations of colours can, for example, be shown to have held quite antithetical connotations in different periods and cultures, and even at the same time and in the same place.).

  • John Gage, Colour and Culture. Practice and Meaning from Antiquity to Abstraction.

two important reviews of the above,

  • by Ludmilla Jordanova, Oxford Art Journal , Vol. 18, No. 1 (1995), pp. 133-137.
  • by Paul Hills, The Burlington Magazine, Vol. 142, No. 1162 (Jan., 2000), p. 45

6 thoughts on “What magic? Where magic? 5c: Green stars (concluded.)

  1. A note on division of the circuit for folio 67v. I’ve noted that one sector (now more likely that for South than for North as previously posited) is twice as large as those directly opposite. If we imagine it notionally a ‘double’ then the number of formal divisions would be eighteen, not seventeen. Measurements by the old Egyptian system is attested still in use in the fifteenth century among the Arab mariners of the eastern seas. Majid has the ‘ibsa (finger) as one and a half degrees, but others as two degrees, with multiples of five giving a palm/’hand’ of ten degrees and thus 20 degrees to the double palm. 360/20 = 18.
    but see:
    Marina Tolmacheva, ‘On the Arab System of Nautical Orientation, Arabica, Vol. 27, No.. 2 (Jun., 1980), pp. 180-192 (JSTOR)

    For a most lucid explanation of the history and practice of sidereal navigation by both Arab mariners, of mariners in the ancient and medieval Mediterranean, and comparison with Chinese practice in the pre- modern era I warmly recommend to novices E.G.R. Taylor’s. study.
    Well written and fascinating in its own right, Taylor manages the rare feat of being meticulous in scholarship while producing text accessible to those with no prior knowledge or interest in the subject. The 1971 edition includes an important essay by Needham on Chinese methods.

    E.G.R. Taylor, The Haven-Finding Art, A History of Navigation from Odysseus to Captain Cook. 2nd edition with an Appendix by Joseph Needham, (London:1971) published by Hollis and Carter Ltd.


  2. I’m now certain that the sun-face’s pointer points South.

    I won’t be publishing more of my research into this folio here; the blog isn’t meant to be about my own work.

    For those wanting to follow the matter further, I note that the two 8-pointed stars in the diagram are, in my opinion, meant for the stars alpha Canis major (Sirius) and Canopus (in Ptolemy a star in Argo, but today described as alpha Carina). Both those stars are in the southern hemisphere. Here’s a photo from the Hubble as illustration. https://en.wikipedia.org/wiki/Canopus#/media/File:Vela_and_Surrounding_Constellations_(ground-based_image).jpg

    Novices will need to understand the different systems for celestial co-ordinates, and the distinction between the theoretical position in astrology and actual position in astronomy. Right ascension and declination are used in both. I’d think it most likely that the chart in fol 67v will be for an epoch between about the 1stC AD and the 15th, and that the most practical angle of approach is to start by using the positions given in Ptolemy’s tables (see link in main post).


  3. phone friendly version of hubble image – add dots after first – and before last- letter group.

    https //commons.wikimedia.org/wiki/File:Vela_and_Surrounding_Constellations_(ground-based_image) jpg


  4. It’s looking increasingly as though these astronomical diagrams – and not only those other sections I’ve previously treated online (but not here) – may remain close to a Hellenistic, and probably Alexandrian origin.
    We know that Claudius Ptolemy relied largely on earlier material, so that’s no particular problem.

    Because it is important for the period (and the risings of Sirius and of Canopus were important year markers for the Ptolemies), I’m going to reproduce here, for future reference, the abstract for a paper delivered in 2012 by Thomas Hockey. He clarified a point important for historical astronomy.
    Note that
    The acronychal rising of Canopus marked the date of the Ptolemaia festival in Egypt.

    Hockey’s paper can be read in full through the SAO/NASA digital library’s ‘ADS’ portal,

    Acronical Risings and Settings
    Hockey, Thomas A.
    A concept found in historical primary sources, and useful in contemporary historiography, is the acronical rising and setting of stars (or planets). Topocentric terms, they provide information about a star’s relationship to the Sun and thus its visibility in the sky. Yet there remains ambiguity as to what these two phrases actually mean.

    “Acronical” is said to have come from the Greek akros (“point,” “summit,” or “extremity”) and nux (“night”). While all sources agree that the word is originally Greek, there are alternate etymologies for it.
    A more serious difficulty with acronical rising and setting is that there are two competing definitions. One I call the Poetical Definition. Acronical rising (or setting) is one of the three Poetical Risings (or Settings) known to classicists. (The other two are cosmical rising/setting, discussed below, and the more familiar helical rising/setting.) The term “poetical” refers to these words use in classical poetry, e. g., that of Columella, Hesiod, Ovid, Pliny the Younger, and Virgil. The Poetical Definition of “acronical” usually is meant in this context.
    The Poetical Definition of “acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun sets, it sets acronically.
    In contrast with the Poetical Definition, there also is what I call the Astronomical Definition. The Astronomical Definition is somewhat more likely to appear in astronomical, mathematical, or navigational works. When the Astronomical Definition is recorded in dictionaries, it is often with the protasis “In astronomy, . . . .”
    The Astronomical Definition of “acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun rises, it sets acronically.
    I will attempt to sort this all out in my talk.

    American Astronomical Society, AAS Meeting #219, id.150.01
    Pub Date: January 2012 Bibcode: 2012AAS…21915001H


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