TABLE OF CONTENTS CHAPTER Unexpected Planets 5 CHAPTER 2 Shifting Starlight 11 CHAPTER 3 Multiple Methods 19 PERSON OF IMPACT John Asher Johnson 22 CHAPTER Ч The Search for an Earth Twin 25 CHAPTER 5 Don't Forget Moons 31 CHAPTER 6 The Planet Next Door 37 CHAPTER 7 The Next Steps 41 FOCUS ON TECHNOLOGY Starshades 44 Focus on Finding Earthlike Planets 46 Glossary 47 To Learn More 48 Index 48
CHAPTER 1 UNEXPECTED PLANETS in the 1980s Earth and the other planets orbiting the sun were the only planets known in the universe Since then astronomers have found thousands of planets circling other stars These planets are called extrasolar planets or exoplanets for short Astronomers had discovered more than 3 500 exoplanets by 2018 Some scientists have found signs that there may be even more planets outside our solar system Many of the first exoplanets scientists discovered were huge gas giants 5
