Sky cultures

日本語

A constellation is a way people joined the stars, and not every people joined them the same way. A sky culture here is a named set of figures made of the same Bright Star Catalogue stars, each with its names and its reading. The 88 constellations of the IAU are the default and nothing about them changes. Three cultures are each their own import, so a page pays only for the one it uses:

A culture goes in as an extra argument to the functions you already use: constellations(culture), constellation(text, culture), starsIn(text, culture), figures(culture) and figureOf(text, culture). Leave it out and you get the 88 of the IAU, as before.

The traditional Chinese sky

import { constellation, constellations, starsIn } from "@johnmorrisdotca/hoshi-stars/constellations";
import { chinese } from "@johnmorrisdotca/hoshi-stars/cultures/chinese";

const dipper = constellation("北斗", chinese);
console.log(dipper.name, dipper.readings.zh, dipper.kind);
console.log(starsIn("beidou", chinese).map((star) => star.name).join(", "));
console.log(constellations(chinese).length, constellations(chinese).filter((a) => a.kind === "mansion").length);
// 北斗 běi dǒu asterism
// Alioth, Dubhe, Alkaid, Mizar, Merak, Phecda, Megrez
// 238 28

北斗 běi dǒu asterism
Alioth, Dubhe, Alkaid, Mizar, Merak, Phecda, Megrez
238 28

constellation and figureOf find a figure by any of its names (Traditional or Simplified characters, pinyin with or without tone marks, the id), ignoring case. The 28 mansions come first, each with its English name and the quarter of the sky it belongs to, the Azure Dragon (azure-dragon), the Black Tortoise, the White Tiger or the Vermilion Bird:

import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { chinese } from "@johnmorrisdotca/hoshi-stars/cultures/chinese";

const horn = figureOf("角宿", chinese);
console.log(horn.asterism.names.en, horn.asterism.group, horn.asterism.readings.zh, horn.stars.map((star) => star.name).join(", "));
// Horn azure-dragon jiǎo xiù Spica, Heze

Horn azure-dragon jiǎo xiù Spica, Heze

Spica is 角宿一, the first star of 角宿. The names of the stars are the first part of the work: a Chinese star name is its asterism and its number in it.

42 of the other asterisms also have an English name, and 41 have partOf: the enclosure they belong to (purple-forbidden, supreme-palace or heavenly-market) or the id of a mansion. Both come from Wikidata, only where it states them; the others have neither, and none is made up:

import { chinese } from "@johnmorrisdotca/hoshi-stars/cultures/chinese";

const canopy = chinese.find("華蓋");
console.log(canopy.names.en, canopy.partOf);
console.log(chinese.asterisms().filter((a) => a.partOf === "heavenly-market").map((a) => a.name).slice(0, 4).join(" "));
// Canopy of the Emperor purple-forbidden
// 七公 列肆 天市左垣 天紀

Canopy of the Emperor purple-forbidden
七公 列肆 天市左垣 天紀

What the catalogue does not hold

Most Chinese asterisms have stars fainter than magnitude 6.0, which the Bright Star Catalogue does not hold, and some have stars our source does not name with a catalogue number. A figure draws only the stars we have, and missing says at least how many it lacks: the largest star number found in the asterism, less the stars held. We cannot always tell which of the two a missing star is, so the demo says "not in our data".

Each star of a Chinese asterism also has its number in it, as its name has it: numbers maps a star's HR number to it ({ 5056: 1, 5107: 2 } for 角宿, Spica being 角宿一). A mansion's star 1 is its determinative star (距星), which our source names for 24 of the 28. The numbers are the source's, repeats and all: 斗宿 has two stars numbered 1 and 天園 two numbered 4, and 三台's pairs share theirs by design. The stars known by a proper name (the Northern Dipper's, 天狼) are numbered by their place in the package's list. The Western and Japanese skies have no numbers.

The demo's sky map has a Mansions switch in the Chinese sky (layers=mansions in the address): the Twenty-Eight Mansions divide the sky by hour circles, and the map draws, dashed like the IAU boundaries in a warm colour, the hour circle (right ascension, J2000) through each mansion's determinative star, its star 1. It draws one only where exactly one star we hold is numbered 1, so 23 of the 28 for now: 氐, 牛, 觜 and 參 have no star 1 in our source, and 斗宿 has two, so they have no circle until a published list gives them. Nothing is guessed. The walls of the Three Enclosures are not drawn yet.

import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { chinese } from "@johnmorrisdotca/hoshi-stars/cultures/chinese";

const guard = figureOf("羽林軍", chinese);
console.log(guard.stars.length, guard.asterism.missing);
// 7 32

7 32

The Palace Guard has about forty-five stars in the traditional lists; the catalogue holds 7 of them. The lines are our own: the stars of an asterism joined by the shortest set of lines that reaches them all, not the traditional drawing. 195 of the 238 asterisms have two stars or more to join; the rest are one star.

Two names are used by more than one asterism in the old lists (柱, 天田, 杵 and 五諸侯). Each is split into the groups of stars that lie together, with ids such as tian1-tian2 and tian1-tian2-2, and a lookup by the bare name finds neither: use the id.

The traditional Japanese sky

import { constellation, starsIn } from "@johnmorrisdotca/hoshi-stars/constellations";
import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { japanese } from "@johnmorrisdotca/hoshi-stars/cultures/japanese";

const subaru = figureOf("すばる", japanese);
console.log(subaru.asterism.name, subaru.asterism.readings.ja, subaru.asterism.names.en, subaru.stars.map((star) => star.name).join(", "));
console.log(constellation("六連星", japanese).id, constellation("Hokuto Shichisei", japanese).aka.join(" "));
console.log(starsIn("鼓星", japanese).length);
// 昴 すばる Subaru Taygeta, Maia, Electra, Merope, Alcyone, Atlas
// subaru 七つ星 ななつぼし 四三の星 しそうのほし
// 7

昴 すばる Subaru Taygeta, Maia, Electra, Merope, Alcyone, Atlas
subaru 七つ星 ななつぼし 四三の星 しそうのほし
7

Each figure has name in its own writing, readings.ja in hiragana, names.en in romaji, aka for the other names it goes by (六連星 for 昴, 七つ星 for 北斗七星), and about, a few English words (the Pleiades). Names, readings and the stars they name come from the pages credited in NOTICE.md; the Japanese awaits a native reader. The lines are our own joins.

The Western sky and the names in every language

import { constellation, starsIn } from "@johnmorrisdotca/hoshi-stars/constellations";
import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { western } from "@johnmorrisdotca/hoshi-stars/cultures/western";

for (const text of ["天龍座", "天龙座", "tiān lóng zuò", "りゅう座", "Draco", "Dragon"]) console.log(text, constellation(text, western).id);
const dra = constellation("Dra", western);
console.log(dra.names["zh-Hans"], dra.names["zh-Hant"], dra.readings.zh, dra.names.ja);
const triangle = figureOf("Summer Triangle", western);
console.log(triangle.stars.map((star) => star.name).join(", "), triangle.segments.length);
console.log(starsIn("夏の大三角", western).length);
// 天龍座 Dra
// 天龙座 Dra
// tiān lóng zuò Dra
// りゅう座 Dra
// Draco Dra
// Dragon Dra
// 天龙座 天龍座 tiān lóng zuò りゅう座
// Vega, Altair, Deneb 3
// 3

天龍座 Dra
天龙座 Dra
tiān lóng zuò Dra
りゅう座 Dra
Draco Dra
Dragon Dra
天龙座 天龍座 tiān lóng zuò りゅう座
Vega, Altair, Deneb 3
3

The Chinese names of the 88 are in the Western culture: the Traditional ones are the National Academy for Educational Research's (Taiwan) astronomy terms, the Simplified ones are those names in the mainland's characters. Both await a native reader.

Your own culture

defineCulture makes a culture from a function that lists its figures. A figure's stars are chains of Bright Star Catalogue (HR) numbers.

import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { defineCulture } from "@johnmorrisdotca/hoshi-stars/culture";

const mine = defineCulture("mine", { en: "Mine", ja: "私の" }, () => [
  { id: "w", name: "W", names: { en: "The W" }, readings: {}, aka: [], about: "", kind: "asterism", group: undefined, missing: 0, chains: [[21, 168, 264, 403, 542]] },
]);
console.log(figureOf("the w", mine).stars.map((star) => star.name).join(", "));
// Caph, Schedar, Navi, Ruchbah, Segin

Caph, Schedar, Navi, Ruchbah, Segin

Pictures of the figures

Each culture is also a set of picture cards in the demo, and the three skies make one set: every card is the same block, a picture, the name in the culture's own writing and one small line under it, and every card is the same height. The small line is the reading (pinyin for a Chinese figure, hiragana for a Japanese one) and the English name where the data has one; a Western card's is its abbreviation and its name in the other language (Ori · オリオン座). Where stars are not in our data, how many are missing (3+ stars not in our data) is in the card's title (what a pointer shows and a screen reader says), not a third line. A figure of which we hold only one star of several has no lines: its card's picture is that star alone, ringed, and its line says 1 star in our data, no lines. The strip above the sky map, the gallery (constellations.html?culture=chinese) and the list (constellation-list.html?culture=chinese) all follow the Sky culture and keep it in the address:

A tap on a card opens that figure on the map in its culture (?culture=chinese&pick=C:bei3-dou3). Search finds a figure by its Chinese name in either writing, pinyin with or without tone marks and spaces, Japanese, kana (katakana against hiragana), romaji or English. The gallery's title and count say which sky it shows (The Chinese sky: 238 figures, 28 mansions and 210 asterisms).

The pictures are drawn by the same renderer as the 88's, from this package's own stars and our own joins of them, so a Chinese or Japanese figure looks like a Western card: a square with the same room round the figure, the neighbouring constellations' boundaries and the faint stars behind it, the same line weight and star sizes, and the figure's stars in full with our own joins between them. A figure of two stars or more stands in a soft dashed outline with a faint wash, the Western card's boundary style. Only the 88 constellations have official boundaries: this outline is the stars' hull with a margin, a drawing aid and not a border. A picture is at least 5 degrees wide, and is widened (to 24 degrees at most) until a neighbouring boundary line crosses it, so every picture has its faint lines. A figure of one star (源氏星 is Rigel, 天狼 is Sirius) is drawn inside its own constellation's picture with the star ringed in the accent colour, never as a lone dot. figureThumbnail draws one, and paddedOutline is the soft outline:

import { figureOf } from "@johnmorrisdotca/hoshi-stars/lines";
import { figureThumbnail, paddedOutline } from "@johnmorrisdotca/hoshi-stars/thumbnails";
import { chinese } from "@johnmorrisdotca/hoshi-stars/cultures/chinese";

const dipper = figureOf("北斗", chinese);
const svg = figureThumbnail({ title: "北斗", stars: dipper.stars, segments: dipper.segments }, { theme: "dark" });
const sirius = figureOf("天狼", chinese);
const ringed = figureThumbnail({ title: "天狼", stars: sirius.stars, segments: sirius.segments }, { theme: "dark" });
console.log(svg.includes("stroke-dasharray"), svg.includes("data-hr"), ringed.includes("data-ring"), paddedOutline(dipper.stars).length > 8);
// true true true true

true true true true

The pictures of the Chinese and Japanese figures are files of the Pages site only (thumbnails/chinese/png/<size>/<look>/<id>.png, 160 and 480 pixels, light and dark: 256 figures, 1,024 PNGs, 15 MB in all), made by pnpm site. The npm package does not ship them; it still ships the 88's. Nothing is fetched at rest: a card's picture is loaded only when the card comes into view.

In the demo

The demo's Sky culture choice (Western, Japanese, Chinese) is kept in the address as culture= (nothing for the Western sky): ?culture=chinese. Picking one redraws the figures and the names on the same stars. Tap a figure, or search for it by any of its names, for its card: its names and reading, what it is, the quarter of the sky, the enclosure or mansion it belongs to where Wikidata says, the constellations it lies in, its bright stars, and, where stars are not in our data, a note that only the stars we have are drawn. The embed page takes the same culture=.

For a child or anyone still learning kanji, the Japanese page of the Chinese sky can put small kana readings (furigana) over 三垣 (the Three Enclosures), 二十八宿 (the Twenty-Eight Mansions), 星官 (asterisms) and the 28 mansions' names, on the strip above the map, the gallery and the list. They are off by default. Turn them on with the Readings switch (ふりがな), shown beside the page's other choices: a press is kept on the device and written to the address. readings=on in the address turns them on for that visit only and leaves what the device keeps alone: constellations.html?culture=chinese&lang=ja&readings=on. The sheets page links to the gallery that way. The English page has no switch, since each card already carries the pinyin and the English.

Where the data comes from

The Chinese asterisms are read from Wikidata (CC0): which star carries which traditional name. The lines, the Western asterisms and the Japanese figures are our own joins of stars. Stellarium's sky-culture files are GPL and CC BY-SA and are not used, nor is any source with non-commercial or share-alike terms. Data and licences has the table, and NOTICE.md names each source with its address and the day it was read.