The Outer Planets Alliance (OPA) is a coalition of organizations and individuals dedicated to the exploration and study of the outer planets in our solar system, including Jupiter, Saturn, Uranus, and Neptune. The alliance promotes scientific research, collaboration, and public outreach to enhance understanding of these distant worlds and their moons. Founded in 2000, the OPA supports missions like NASA's Juno and Cassini-Huygens, which have provided valuable data about the atmospheres, rings, and potential habitability of these planets. The alliance aims to foster international cooperation in planetary science and encourage future exploration initiatives.