Exploring the sky: Scale of the cosmos, from solar system to galaxy to universe; User's guide to the sky, patterns and cycles; Circles around the Earth become orbits around the sun; Astronomical telescopes and instruments, extending humanity's vision -- Stars: Sun light and sun atoms; Family of stars; Structure and formation of stars; Deaths of stars -- Galaxies and cosmology: Milky way galaxy; Galaxies; Cosmology in the 21st century -- Solar system: Origin of the solar system; Comparative planetology of the terrestrial planets; Comparative planetology of the outer planets -- Life: Life on other worlds -- Afterword -- Appendices: Units and astronomical data; Observing the sky -- Glossary