These are Jupiter, Saturn, Uranus, and Neptune-the outer planets of our solar system, which, in turn, hold a treasure trove of information regarding planetary origin and the dynamics governing our solar system. These gas giants, with their very complex atmosphere and mysterious moon, have been studied through several pioneering space missions that have gone further in our study of these cosmic worlds.
Most studied of all is Jupiter, the largest planet of our solar system. Launched in 2011, NASA's Juno mission has been orbiting Jupiter since 2016 and providing never-before-seen data about this gas giant's atmosphere, magnetic field, and gravitational field. Therefore, the revelations from Juno up to date include unknown cyclones at its poles and how the weather systems of the planet are dynamic.
Saturn has also been explored. The mission, Cassini-Huygens, was operated by NASA along with the European Space Agency in collaboration between the years 2004 and 2017. During those years, Cassini imaged Saturn, as well as Saturn's ring system with far greater resolution, while taking very detailed data about this planet's rings, atmosphere, and many moons. The probability is the success of the mission was the Huygens probe that landed on Titan, Saturn's biggest moon. For example, the thick atmosphere and lakes of methane in Titan hint toward complex chemistry with possible clues to prebiotic conditions.
The outer planets too come in view: only one mission, namely, Voyager 2 flown by NASA, visited Uranus and Neptune, in that order in 1986 and 1989. Due to a lack of followup missions, however, little is known about these ice giants. But Voyager 2 brought home some amazing data: fascinating features like Neptune's Great Dark Spot and Uranus's tilt. Scientists have argued for new missions to revisit those mysterious worlds, as interest in the outer planets grows.
While extraterrestrial applications extend far beyond the sub-field of planetary science, study of outer planets has drawn special attention to the moon's potential as a habitable environment, particularly on Europa, which orbits Jupiter, and Enceladus orbiting Saturn, both of which are endowed with oceans beneath icy crusts, raising interesting questions about existence beyond Earth. Then, in the next century, missions such as the NASA's Europa Clipper will observe these distant satellites then search them for signs of life and further explore the geological features of those moons.
Overall, the study of the outer planets may be considered as the frontiers of planetary science since it can give information concerning how our solar system was born and perhaps the possible conditions that can harbor extraterrestrial life. Thus, the mission into these faraway planets will unlock some secrets concerning the gas giants and their satellites, thereby enlarging human knowledge of the universe.
