This is Meeus' older book, originally written in the days when programmable calculators were the most sophisticated computing machines available to the general public, the mid-to-late 1970s. This is a plus for those who are still learning the math and the programming skills necessary to solve astronomy problems, because Meeus spends some effort making sure the reader is aware of common beginner's mistakes. Otherwise, the text is packed full of practical details on the computation of planetary and lunar positions, calendar and time problems, and various miscellaneous good-to-know methods, like interpolation and curve fitting. He introduces the older Ephemeris Time system, which is easier to deal with than the new relativity-based time systems currently used by the big Almanacs. Most of the formulae for converting coordinates from one system to another, precession, planetary abberations, calendars, and similar, which do not change much over time, are perfectly accurate and useful. The planetary orbital models he gives are the older theories of Newcomb, Leverrier, and Gaillot of about a century ago, truncated to keep them short enough for publication, and to fit into the memories of those programmable calculators. The lunar model is, I think, Brown's of the same time frame. The truncation is severe enough that the positions produced by the formulae are only good to a few arcseconds accuracy, worse for the outer planets, and he gives no orbit for Pluto at all. The book is relatively small in size, which is nice. In the decades after this book, the new computer-calculated planetary theories of JPL and the Observatoire de Paris were released, and Meeus moved on to his newer book, "Astronomical Algorithms".