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astro201, blog6, ganymede, jupiter, magnetosphere, moon, ocean, solar system
One of the largest satellites in the solar system is Jupiter’s moon Ganymede. Though Ganymede is classified as a moon because it orbits a planet, it actually shares more features with the Earth than with our Moon. Ganymede is nearly as large as Mars and dwarfs Mercury and Pluto in terms of radius. Astronomers think that Ganymede’s surface is part of a thick layer of ice, but it also has a layer of rock beneath this ice – a more solid version of Earth’s mantle – and an inner core made of metal that gives Ganymede a magnetosphere. Though there is a very thin atmosphere, scientists have found evidence of oxygen on the surface of the planet.
Jupiter’s largest moon, Ganymede (Nasa Solar System Exploration)
Since the Hubble Space Telescope has been transmitting images of Ganymede’s surface, astronomers have established growing confidence that there may be a liquid ocean of salt water beneath the icy surface of the planet. An ocean like this would minimize the effects of Jupiter’s magnetic field interrupting that of Ganymede’s, and the effects observed thus far support this claim. Though Ganymede’s aurora should shift by about six degrees due to pull from the magnetic field of Jupiter, they only shift by two degrees, indicating the presence of a salt-abundant ocean. This ocean would likely be found about 100 kilometers beneath the icy surface of the planet.
Although this idea is still forming, there will be more concrete evidence for Ganymede’s ocean after the dispatch of Europe’s JUICE (Jupiter Icy Moon Explorer) spacecraft, which should launch in the early 2020s and arrive around Jupiter shortly after 2030. The goal for JUICE is for the craft to fly by Jupiter and some of the planet’s other moons, and then fall into orbit around Ganymede in order to send pictures and other data of the moon back to Earth.
Sources: NASA Solar System Exploration, BBC World
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