Fig 1.
The diversity of constellations line figures.
Traditional Chinese (top) and ancient Babylonian (bottom) constellations for the same southern sky: declinations [−90°, 20°], right ascensions [90°, 270°]. The choice of stars and lines differs. Some constellation names removed for clarity.
Fig 2.
The 56 cultures are shown with: name, the date of documentation, and the number of constellations (or asterisms) with at least one line. Sky cultures with global reach are highlighted at the bottom.
Fig 3.
Constellations features aggregated per sky culture.
The culture size (constellation count) is on the left. Four constellation features (s1, s12, s16, and s17) are then shown via their averages and standard deviations per culture. The global average of each statistic is marked with a dotted line. The horizontal scales for the first two statistics are logarithmic, and the rest linear.
Fig 4.
The map of constellation features in two embedded dimensions.
All plots show the same embedding. One point represents one constellation. (top) The gradient of each constellation feature, as projected in the low-dimension space. Twelve constellation features are shown. (bottom) A summary of the clusters.
Fig 5.
Examples of constellations over the embedding.
In the background, in light blue, the embedding of all constellations, the same as in Fig 4. In the foreground, we show example constellations: (1) black markers for IAU constellations [11]; (2) orange markers for other cultures.
Fig 6.
Visual signatures by culture (question I.1).
(top) Constellations from example cultures are shown in the foreground, over the background of all other constellations. (bottom) The similarity graph for cultures. The node size is proportional to the number of constellations per culture, and the edge width to the similarity Δ.
Table 1.
Summary of sky cultures.
Fig 7.
Visual signatures by practical use (question I.3).
(top) Constellations per use are shown in the foreground, over the background of all other constellations. (bottom) The similarity graph between practical uses. The node size is proportional to the number of constellations per use, and the edge width to the similarity Δ.
Fig 8.
Visual signatures by phylogeny (question I.4).
(left) Constellations with common phylogeny are shown in the foreground, over the background of all other constellations. The smallest three phylogenies are not shown: Sami (3 constellations), Egypt (26), and Austronesia (27). (right) The similarity graph between phylogenies. The node size is proportional to the number of constellations per phylogeny, and the edge width to the similarity Δ.
Fig 9.
Per root star, the diversity index H among all constellations with that star (on the left y axis with triangles), and the number of constellations with that star (on the right y axis with dashes). Value 0.5 for diversity is marked with a dotted line, and the diversity markers are coloured differently above and below this. The mean diversity is H = 0.568. The alternating background emphasises root stars from the same IAU constellation.
Fig 10.
The diversity of constellations over the root star α Ori (II).
In the background, in light blue, the embedding of all constellations. The IAU constellation Orion is shown at the top left, with α Ori emphasised. In the foreground, there are examples: black stars mark all constellations over α Ori, of which some are also shown, to scale.
Fig 11.
Regional timeline for line figures.
The centuries AD are marked at the bottom, on a non-linear scale. Dark blue time intervals are recent periods, during which line figures are documented. They are preceded by periods of development or transition (in light blue), during which important sources for line figures are marked. In E Asia, the circle-and-line representation is native. In Europe and W Asia, line figures developed out of pictographs, alongside the development of modern astronomy. In the Americas and the Pacific, they were likely introduced under Western influence.
Table 2.
Parameters for the t-distributed Stochastic Neighbor Embedding (t-SNE).