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In his 1805 book Celestial Mechanics, in addition to laying out his mathematical argument for the resonant orbits of Io, Europa, and Ganymede, Laplace was able to use perturbations on the orbit of Io by Europa and Ganymede to provide the first estimate of Io's mass, 1.73 × 10 −5 of the mass of Jupiter, which was one-quarter of the modern value.
The Rare Earth hypothesis argues that planets with complex life, like Earth, are exceptionally rare.. In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the origin of life and the evolution of biological complexity, such as sexually reproducing, multicellular organisms on Earth, and subsequently human intelligence, required an improbable combination of astrophysical ...
The largest, Ganymede, is the largest moon in the Solar System and surpasses the planet Mercury in size (though not mass). Callisto is only slightly smaller than Mercury in size; the smaller ones, Io and Europa, are about the size of the Moon. The three inner moons — Io, Europa, and Ganymede — are in a 4:2:1 orbital resonance with
On 8 September 2014, NASA reported finding evidence of plate tectonics on Europa, a satellite of Jupiter—the first sign of subduction activity on another world other than Earth. [2] Titan , the largest moon of Saturn , was reported to show tectonic activity in images taken by the Huygens probe , which landed on Titan on January 14, 2005.
Ganymede, or Jupiter III, is the largest and most massive natural satellite of Jupiter, and in the Solar System.Despite being the only moon in the Solar System with a substantial magnetic field, it is the largest Solar System object without a substantial atmosphere.
(Ice has less tensile strength than rock, and is deformed at lower pressures and temperatures than rock.) The evidence is perhaps strongest for Ganymede, which has a magnetic field that indicates the fluid movement of electrically conducting material in its interior, though whether that fluid is a metallic core or a subsurface ocean is unknown ...
The book describes Ganymede as having about 1 ⁄ 3 Earth gravity but in reality it is only about 1 ⁄ 7. Heinlein also postulated that the surface of Ganymede was volcanic rock like the Moon . Subsequent discoveries have shown that Ganymede's crust is actually almost 90 percent ice or frost, covering a subsurface ocean.
Ganymede was shown to possess a magnetic field and the spacecraft found new evidence for exospheres around Europa, Ganymede, and Callisto. Galileo also discovered that Jupiter's faint ring system consists of dust from impact events on the four small inner moons. The extent and structure of Jupiter's magnetosphere was also mapped.