Why the stars twinkle and the sky is blue, why you can't walk under the arch of a rainbow, how you can see the sun when it isn't there or see an object that is ""actually"" below the horizon, and why five suns were seen in the sky on September 15, 1851: Heuer explains these and less commonplace puzzles as he directs readers' attention to the many spectacular atmospheric effects visible to the naked eye. ""Wonders"" run from the very familiar (rainbows and the mirage of water seen on hot surfaces) to the rare and awesome ""broken specter"" and sun cross, and they include many relatively frequent but rarely noticed phenomena--halos, ""luminescent trees,"" and the green flash after sunset. Heuer has observed many of these occurrences, and his personal accounts (as well as eye-witness reports from other observers) describe not only what the phenomena look like but also how it feels to come upon them. The book is divided into 22 short chapters, each on a different type of effect and each containing a readable mixture of description and history with a concise but not skimpy explanation of the effects and the scientific principles behind them. The text is well illustrated with 19th-century etchings, which nicely delineate the observed effects, and with a few black-and-white photos where helpful.