Milky Way

The bright band that crosses the whole sky is the disc of the home galaxy seen from inside, and almost every tradition has decided what it is. In China it is the Silver River, or the Celestial River, the stream that separates the Weaver Girl from the Herdboy, the stars Vega and Altair, who are permitted to meet across it one night each year at the Qixi festival. In Greece and Rome it was the road of milk, spilled from the breast of Hera, and the Latin name Via Lactea is the direct ancestor of the English Milky Way.

Medieval England read it as a road as well, but a particular one: Chaucer records that people called it Watling Street, the great highway laid across the sky to match the one laid across the land. In the Andes it is Mayu, the river, and Quechua communities describe its dark clouds as animals drinking from it, with the river carrying water through the sky and returning it to earth as rain.

Across much of eastern North America it is the Path of Souls, the road the dead walk toward the land of the ancestors. To the Maori it is Te Ika Roa, the long fish stretched across the night. Each of these readings is held on this page as its own tradition-scoped fact, because they are different claims about one object, and the atlas does not choose among them in its own voice.

Most constellations are patterns of stars. A smaller family of figures, read mainly in the southern hemisphere where the galactic centre rides high, works the other way: the figure is a dark shape, a cloud of interstellar dust silhouetted against the glow of the Milky Way, and the band itself is the canvas the figure is drawn on. The Andean sky holds the fullest recorded set.

The Yacana, the llama, is the largest of them, rising with two bright stars for eyes; Machacuay the serpent and Yutu the tinamou follow it in a fixed procession along the river Mayu, and Andean observers time the year by which animal stands where. Aboriginal Australia reads the Emu in the Sky the same way: the head is the dense dark patch Western astronomy calls the Coalsack, beside the Southern Cross, and the neck and body run down the length of the band.

None of these figures contains a single star. The atlas records each of them as a constellation in its own register, linked to this page as figures contained in the Milky Way, because the band is what makes them possible. Modern astronomy gives the shadows a cause without changing the observation: the dark shapes are lanes of dust in the galactic disc, dense enough to swallow the light of the stars behind them, the same material from which new stars condense.