Exoplanet Discovery and Characterization

How did we get here? Are we alone? A fundamental milestone in answering these questions is the origin of Earth, an event that we are just now contextualizing, thanks to the discovery of thousands of exoplanets. Using telescopes, a worldwide community of astrophysicists is investigating how the thousands of known planetary systems formed, what they reveal about the origin of our solar system, and whether these distant worlds could harbor life. As part of our investigation, we are discovering Earth-sized planets with rocky surfaces amenable to life as we know it. Such worlds appear to be common, with approximately one in five stars harboring such a planet, yielding an estimated 17 billion worlds that might resemble Earth in our galaxy alone. Many of these worlds form in intriguing patterns of regular sizes and orbital spacing. These patterns, which we call "peas in a pod," are mostly absent from the solar system, but resemble a theorized early generation of solar system planets thought to have been destroyed by Jupiter. Meanwhile, Earth's extensive surface liquid water, which is a key aspect of its suitability for life, is attributed to the gravitational influence of Jupiter. How was Earth's water delivered, and can we expect the small, rocky exoplanets we have discovered to be similarly endowed? The discovery of patterns among the exoplanets is ushering a new era, one in which we hope to contextualize Earth's physical origin and guide humanity's next steps in the search for life.