So, here’s the thing you need to understand about constellations…
Every year the International Association of Astronomers assemble for their annual conference. On the final night, always timed to coincide with the new moon, there is a grand feast with much drinking and merriment. Shortly before 11pm, a hush gathers over the crowd and the youngest astronomer hands a pencil and an unlabelled map of the night sky to each of the gathered scholars.
The Astronomer Royal takes the stage and recites an ancient poem — words that I am not allowed to repeat here. He opens a time-worn wooden box and removes a pewter 20-sided dice. The Astronomer Royal holds the instrument of chance briefly above his head, so all the heavens can see it, before tossing the dice into the air. If it results in a natural 20, the ritual begins.
In complete silence each astronomer redraws the map of the heavens from memory. Most reproduce the existing constellations perfectly. Some make small mistakes. The occasional trickster will ignore all convention and reinvent the sky. As the clocks strike midnight, the youngest astronomer gathers the maps and delivers them to the Astronomer Royal. A single map is selected at random and immediately becomes the authoritative representation of the night sky.