Astronomy is the scientific study of space, including the planets, stars, galaxies, comets and nebulae. Understanding astronomy begins with an overview of the history of this science and the early astronomers. Astronomy then covers the essential concepts, including: gravity, telescopes, Kepler's Laws, the Universal Law of Gravitation, and the doppler effect. The Astronomy DVD 2-Pack includes Astronomy Part 1 and Part 2 at a discounted price.