Abstract External energy inputs into all planetary upper atmospheres (including more than a half dozen moons with atmospheres) are comprised of combinations of solar EUV, soft x-rays, solar energetic particles, solar wind charged particles, magnetospherically accelerated particles, solar wind electric field, interplanetary dust particles as well as propagating lower atmosphere disturbances. Each input has analogous physical interactions with all planetary ionospheres and upper atmospheres, but the integrated consequences of the multiple energy inputs vary from planet to planet. The Earth forms the framework for most fundamental processes because of extensive measurements of the effects of each of the inputs. However the conditions at Earth are far different from those at the carbon dioxide atmosphere of magnetic field-free, slow-rotating Venus, the carbon dioxide atmosphere of Mars with patchy remnant magnetic fields, while the outer planets have hydrogen atmospheres, are fast rotating with intrinsic magnetic fields, and encompass moons that interact with the magnetospheres and have exotic atmospheres. Although the physical processes are known, our understanding of our solar system's ionospheres diminishes with increasing distance from the Sun.

The various processes which generate magnetic fields within the Jupiter system are exemplary for a large class of similar processes occurring at other planets in the solar system, but also around extrasolar planets. Jupiter's large internal dynamo magnetic field generates a gigantic magnetosphere, which is strongly rotational driven and possesses large plasma sources located deeply within the magnetosphere. The combination of the latter two effects is the primary reason for Jupiter's main auroral ovals. Jupiter's moon Ganymede is the only known moon with an intrinsic dynamo magnetic field, which generates a mini-magnetosphere located within Jupiter's larger magnetosphere including two auroral ovals. Ganymede's magnetosphere is qualitatively different compared to the one from Jupiter. It possesses no bow shock but develops Alfvén wings similar to most of the extrasolar planets which orbit their host stars within 0.1 AU. New numerical models of Jupiter's and Ganymede's magnetospheres presented here provide quantitative insight into the processes that maintain these magnetospheres. Jupiter's magnetospheric field is approximately time-periodic at the locations of Jupiter's moons and induces secondary magnetic fields in electrically conductive layers such as subsurface oceans. In the case of Ganymede, these secondary magnetic fields influence the oscillation of the location of its auroral ovals. Based on dedicated Hubble Space Telescope observations, an analysis of the amplitudes

would have been launched in 2023. The mission was cancelled due to a lack of funding in 2017. Cold trap (astronomy) Moons of Jupiter Galilean moons (the Ganymede is a natural satellite of Jupiter and is the largest and most massive moon in the Solar System. Like Saturn's largest moon, Titan, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io, or Earth's Moon due to its lower density compared to the three. Ganymede orbits Jupiter in roughly seven days and is in a 1:2:4 orbital resonance with the moons Europ Ganymede is a natural satellite of Jupiter and is the largest and most massive moon in the Solar System. Like Saturn's largest moon, Titan, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io, or Earth's Moon due to its lower density compared to the three. Ganymede orbits Jupiter in roughly seven days and is in a 1:2:4 orbital resonance with the moons Europa and Io, respectively. Ganymede is composed of silicate rock and water in approximately equal proportions. It is a fully differentiated body with an iron-rich, liquid metallic core, giving it the lowest moment of inertia factor of any solid body in the Solar System. Its internal ocean potentially contains more water than all of Earth's oceans combined. Ganymede is the only natural satellite in the solar system to possess an internally generated magnetic field. It is probably created by convection within its core, and influenced by tidal forces from Jupiter's far greater magnetic field. Ganymede has a thin oxygen atmosphere that includes O, O2, and possibly O3. Atomic hydrogen is a minor atmospheric constituent. Whether Ganymede has an ionosphere associated with its atmosphere is unresolved. Ganymede's surface is composed of two main types of terrain, the first of which are lighter regions, generally crosscut by extensive grooves and ridges, dating from slightly less than 4 billion years ago, covering two-thirds of Ganymede. The cause of the light terrain's disrupted geology is not fully known, but may be the result of tectonic activity due to tidal heating. The second terrain type are darker regions saturated with impact craters, which are dated to four billion years ago. Ganymede's discovery is credited to Simon Marius and Galileo Galilei, who both observed it in 1610, as the third of the Galilean moons, the first group of objects discovered orbiting another planet. Marius soon named it after Ganymede, a Trojan prince desired by Zeus, who carried him off to serve as cupbearer to the gods. Beginning with Pioneer 10, several spacecraft have explored Ganymede. The Voyager probes, Voyager 1 and Voyager 2, refined measurements of its size, while Galileo discovered its…