Water vapor on Ganymede
Scientists have found the first evidence of water vapor on Ganymede, a world orbiting Jupiter and the largest and most massive moon in our solar system. They said this discovery is a step toward understanding the habitability of moons orbiting giant planets. At noon around Ganymede’s equator, temperatures apparently get warm enough for parts of the moon’s icy crust to sublimate. That is, the ice goes directly from a solid to a gas, releasing water vapor.
The researchers made the discovery with the help of archival data from the Hubble Space Telescope, together with some new data. They published their findings on July 26, 2021, in the peer-reviewed journal Nature Astronomy.
In 1998 and 2010, the Hubble Space Telescope observed Ganymede in ultraviolet (UV) light. Images from both observations revealed an aurora zone for Ganymede, a sign that this large moon has a permanent magnetic field, produced by an iron core. Ganymede also orbits within Jupiter’s magnetic field. But the regions of active aurorae on Ganymede looked different in 2010 than they did in 1998. And scientists thought these differences might be due to the presence of atomic oxygen in Ganymede’s thin atmosphere.
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