Although Astronomy has been around for more than 5,500 years, astronomers say that we've learned more than 90% of what we know about the universe in just the last 50 - and much of that in the last decade! "The Complete Idiot's Guide[registered] to Astronomy", Fourth Edition, continues to be the most comprehensive introduction to the topic, covering all the latest advances and discoveries, including: the demotion of Pluto and promotion of Ceres as planetary objects; breakthrough evidence of recent water flow on Mars; new developments in asteroid-tracking programs; new information on the nature and shape of our universe; mind-bending theories concerning multiple universes; and information on the latest telescopes. As a bonus, this book includes a fascinating CD ROM with more than 200 of the most spectacular images from NASA, star maps and other tools for backyard astronomers.