From our own solar system to the edges of the universe, 50 Astronomy Ideas You Really Need to Know is your introduction to the most important concepts, discoveries and mysteries in astronomy. How did the universe begin? Where did the Moon come from? What happens in the heart of a black hole? Why are gravitational waves so significant? And is there life elsewhere in the cosmos? In fifty fascinating essays covering the central ideas of astronomy and cosmology, accompanied by diagrams, definitions of essential terms and timelines of key discoveries, this book examines the nature and variety of our universe - the life cycle of stars, the formation of planets, the structure of galaxies and the puzzles of dark matter and the multiverse. Expansive and illuminating, 50 Astronomy Ideas You Really Need to Know is the complete guide to the birth, life and possible death of the cosmos.