The stars still wear his letters
This is Orion as Johann Bayer engraved him in 1603 — the hunter drawn over a field of stars fixed in their true places.1 Bayer was a lawyer in Augsburg who did astronomy for love of it, and his Uranometria was the first atlas to chart the entire sky, north and south.2
A sky measured by eye
The star positions came from Tycho Brahe's catalogue — about a thousand stars, the most exact figures of the age, every one taken by naked eye.3 Bayer printed them six years before the telescope existed.4 This is the sky as the unaided eye had learned to hold it, at the last moment before the lens changed what a star could be.
The letters that stuck
Bayer did one more thing that outlived him. Within each constellation he lettered the stars in Greek — α, β, γ — roughly brightest to faintest.5 It was the first systematic way to name a star, and it never went away. Four centuries on, Betelgeuse, Orion's red shoulder, is still Alpha Orionis; Rigel, the blue foot, is still Beta.6 Astronomers redrew the constellation borders in 1930 and kept his letters.7
The plate
The figure was cut into copper by Alexander Mair and printed from the plate.8 The title page stated the method flatly: an atlas "containing charts of all the constellations, drawn by a new method, engraved on copper."9 Not a decoration of the sky — a measurement of it.
What you wear is that plate: the hunter, the true stars, and the Greek letters we still say out loud.
Notes & sources
- Johann Bayer's Orion plate, Uranometria (1603).
- Johann Bayer (1572–1625), lawyer and amateur astronomer of Augsburg; Uranometria (1603) was the first star atlas to cover the whole celestial sphere. Wikipedia; Britannica.
- Star positions drawn from Tycho Brahe's catalogue (~1,000 stars), the most accurate of the pre-telescopic era.
- Published in 1603, about six years before the telescope (Lippershey, 1608). Britannica.
- Bayer lettered the stars of each constellation in Greek (α, β, γ…), roughly brightest to faintest.
- Betelgeuse = Alpha Orionis; Rigel = Beta Orionis. Wikipedia.
- The modern constellation boundaries were fixed by the IAU in 1930; Bayer's letters remain in use.
- Engraved by Alexander Mair; printed at Augsburg by Christoph Mang, 1603.
- Title-page subtitle: "…omnium asterismorum continens schemata, nova methodo delineata, aereis laminis expressa."