Challenges of astronomy

the long version

A unique collection of thirty experiments ranging from ancient astronomy to cosmology, each containing one or more challenges for the reader. The progression here is from the Earth outward through the solar system to the stellar and galactic realm. Topics include the shape of the sky; Stonehenge as a stone-age abacus; determining the size of the Earth; the distance of the moon, stars and planets; planetary mass, density, temperature and atmosphere; the speed of light; the nature of the quiet and active sun; photometry and spectroscopy; star clusters and variable stars; and fundamental properties of stars.