干旱区生态环境知识资源中心

Just 14 years ago the Solar System represented the only known planetary system in the Galaxy, and conceptions of planet formation were shaped by this sample of one. Since then, 320 planets have been discovered orbiting 276 individual stars. This large and growing ensemble of exoplanets has informed theories of planet formation, placed the Solar System in a broader context, and revealed many surprises along the way. In this review I provide an overview of what has been learned from studies of the occurrence, orbits, and physical structures of exoplanets. After taking a look back at how far the field has advanced, I will discuss some of the future directions of exoplanetary science, with an eye toward the detection and charactarization of Earth-like planets around other stars.