It was one of humanity’s greater vanities that we ever questioned whether there are any planets in the universe beyond the eight in our little solar system. Our sun is a perfectly ordinary star, residing in a perfectly ordinary galaxy, out in the suburban fringes of one of the Milky Way’s spiral arms. There are more than 100 billion other stars in the galaxy and, in turn, up to two trillion galaxies in the universe. The physics are the same everywhere, and if our solar system could spin up