The Astronomers' Magic Envelope is an introduction to astrophysics emphasizing general principles and orders of magnitude. The envelope is metaphorical, of course --- it could also be a Python IDE. We begin with the Enlightenment-era insight that the orbits of the planets are easy, but the orbit of the Moon is a real headache, and continues to deterministic chaos. Then we proceed to spacetime and black holes, how stars work, and beyond to 21st-century developments on microwave background and gravitational waves. Check out the preprint.
The pessimistic comment by Simon Newcomb at the end of the 19th century, which we quote in Chapter 4, comes from an address on The Place of Astronomy Among the Sciences. Thanks to Barbara Ryden for pointing this out.
The last equation in Chapter 4 needs an extra constant factor of m4/(3π2). Corrected by Nastassia Grimm
Between equations (4.33) and (4.34): the sum of inverse fourth powers should be π4/90 (not π2/90). Corrected by Ugur Gültekin.
Further corrections welcome.