What we know, and how
Measured, worked out, or drawn — and always said which
Nobody has ever seen the Milky Way from outside: we live inside it. What we know of it comes from measuring the stars round us one by one and working out the rest. Every place here is marked for which of the three it is.
- MeasuredWhere 32,639 real stars are and how bright, from the Hipparcos satellite and the catalogues that came before it; where each planet and moon is at this moment, from its orbit; the distances to the nebulae and black holes.
- Worked outHow light bends round a black hole, how long it takes to reach you from each place, how big things are against each other, and when the next eclipse falls.
- DrawnThe galaxy seen from outside, whose arms follow their measured spiral; the shapes of the nebulae and the surfaces of distant worlds, drawn from what is known of their kind. Each says so on its card.