People must have watched the skies from time immemorial. Human beings have always shown intellectual curiosity in abundance, and before the invention of modern distractions people had more time-and more mental energy-to devote to stargazing than we have. Megaliths, Chinese oracle bones, Babylonian clay tablets, and Mayan glyphs all yield evi dence of early peoples' interest in the skies. To understand early astronomy we need to be familiar with various phenomena that could-and still can-be seen in the sky. For instance, it seems that some early people were interested in the points on the...