Meet Petrus Apianus’ “Astronomicum Caesareum”: a rare masterpiece of both bookmaking and 16th century astronomy. We’re lucky enough to have one of only about 40 original copies in the world. 📚 This book is filled with intricate paper volvelles that each demonstrate a different kind of astronomical observation. They allow the reader to pretend that they’re using a real astrolabe—kind of like a 1540s style pop-up book! 😉 It is also one of the most comprehensive collections of 16th century astron