Written by an expert team of contributors under the editorship of Ian Ridpath, this text covers everything from black hole to white dwarf. It should be of value to students, professionals, and amateur astronomers seeking a comprehensive source of helpful information. There are 4000 entries, from astrophysics and cosmology to galaxies and time, and major entries include Big Bang theory, comet, eclipse, Magellanic Clouds, Mars, quasar, radio telescope, relativity, and variable stars. Up-to-date coverage includes space missions and recently named Solar System objects. As well as world-wide coverage of telescopes and observatories there are also biographical entries on eminent astronomers from Copernicus to Edwin Hubble.