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From page 265... ... 10 Question 7: Giant Planet Structure and Evolution What processes influence the structure, evolution, and dynamics of giant planet interiors, atmospheres, and magnetospheres? The giant planets comprise 99.5 percent of the mass of the solar system, apart from the Sun, and 96 percent of the solar system's total angular momentum.1 They are the most massive remnants of accretion from the Sun's nebular disk and to have played a substantial role in shaping the overall architecture of the solar system. Read the entire page →
From page 266... ... 266 ORIGINS, WORLDS, AND LIFE FIGURE 10-1 Interiors of Jupiter, Saturn, Uranus, and Neptune (not to scale) Read the entire page →
From page 267... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 267 chemical interactions, determination of their enrichment compared to that of the major gases is an essential clue to understanding giant planet evolution (Guillot and Gautier 2015) Read the entire page →
From page 268... ... 268 ORIGINS, WORLDS, AND LIFE FIGURE 10-2 Atmospheric composition varies in the vertical direction owing to thermochemistry in the deep troposphere, cloud chemistry in the upper troposphere, and photochemistry in the stratosphere. Stratospheric water comes from external (ring rain and cometary) Read the entire page →
From page 269... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 269 may separate from hydrogen (Bailey and Stevenson 2021) , which would affect the structure, chemistry, and evolution of these planets. Read the entire page →
From page 270... ... 270 ORIGINS, WORLDS, AND LIFE FIGURE 10-3 Visualizations of the interior structure (top panels) and magnetic fields (bottom panels) Read the entire page →
From page 271... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 271 Q7.2a How Does Composition Change with Depth in Giant Planet Interiors? Recent measurements of Jupiter's and Saturn's gravitational fields, as well as observations of waves in Saturn's rings, have revealed that both planets have dilute cores. Read the entire page →
From page 272... ... 272 ORIGINS, WORLDS, AND LIFE Given the spatial complexity of the ice giant dynamos, measurements of Uranus's and Neptune's magnetic fields would likely be a powerful tool to constrain their internal dynamics (Soderlund and Stanley 2020) Read the entire page →
From page 273... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 273 Strategic Research for Q7.2 • Determine the interior structure and composition of Uranus and Neptune using gravity and magnetic field mapping. • Search for the locations and extent of discrete layers in the deep interior in all four giant planets, using planet/ring seismology (i.e., the ability to detect planetary seismic waves from perturbations in the motion of ring particles) Read the entire page →
From page 274... ... 274 ORIGINS, WORLDS, AND LIFE FIGURE 10-4 Cloud bands, zonal winds, and deep rotation on the outer planets. The wind profiles are shown at the same scale for each planet and show zonal jets reaching 200–400 m/s; Jupiter and Saturn exhibit prograde equatorial jets, while Uranus and Neptune's are retrograde. Read the entire page →
From page 275... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 275 Q7.3c How and Why Do Discrete Meteorological Features (e.g., Storms and Vortices) Evolve? Read the entire page →
From page 276... ... 276 ORIGINS, WORLDS, AND LIFE to centuries-long intervals between convective outbursts, a potential explanation for apparent differences in the intrinsic luminosities of Uranus and Neptune (Smith and Gierasch 1995; Li and Ingersoll 2015) Read the entire page →
From page 277... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 277 FIGURE 10-5 Comparison of size and geometry of the giant planet magnetospheres. For scale, the purple box at Jupiter spans ~1 million km, and the Uranus box spans ~650,000 km. Read the entire page →
From page 278... ... 278 ORIGINS, WORLDS, AND LIFE contributions coming from the solar wind imposed electric field (Khurana et al. 2004; Kivelson and Bagenal 2007; Gombosi et al. Read the entire page →
From page 279... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 279 Q7.4d How Do External Inputs and Local Ion Chemistry Produce the Complex Variability Observed in Ionospheres? Although overall composition should be similar in the ionospheres of the giant planets, the insolation, seasonal forcing, magnetic field configuration, and ring influxes are very different. Read the entire page →
From page 280... ... 280 ORIGINS, WORLDS, AND LIFE Q7.5b How Is Atmospheric Composition Influenced by Ring Rain, Large Impacts, and Micrometeoroids? Measurements made by Earth-based telescopes and the Cassini spacecraft reveal a large flux of material into Saturn's atmosphere from the rings, which may provide a total water flux to Saturn of 10,000 kg/s (Moore et al. Read the entire page →
From page 281... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 281 REFERENCES Adriani, A., A Read the entire page →
From page 282... ... 282 ORIGINS, WORLDS, AND LIFE Hueso, R., and A Sánchez-Lavega. Read the entire page →
From page 283... ... QUESTION 7: GIANT PLANET STRUCTURE AND EVOLUTION 283 Moll, R., P Garaud, C Read the entire page →
From page 284... ... Q8 PLATE: Cassini's final image mosaic of Saturn, taken 48 hours before the mission ended with the spacecraft entering Saturn's atmosphere in 2017. SOURCE: Courtesy of NASA/JPL-Caltech/Space Science Institute. Read the entire page →

From page 265...

... 10 Question 7: Giant Planet Structure and Evolution What processes influence the structure, evolution, and dynamics of giant planet interiors, atmospheres, and magnetospheres? The giant planets comprise 99.5 percent of the mass of the solar system, apart from the Sun, and 96 percent of the solar system's total angular momentum.1 They are the most massive remnants of accretion from the Sun's nebular disk and to have played a substantial role in shaping the overall architecture of the solar system.