Previous research has suggested Ganymede, the largest moon and the ninth-largest object in our solar system, “contains more water than all of Earth’s oceans put together. Although, “the moon is 2.4 times smaller than our planet.” But the surface of Ganymede is a frozen water ice shell. So cold that temperatures can reach negative 300 degrees Fahrenheit (-184 degrees Celsius). Researchers say roughly 100 miles (161 kilometers) below this crust there is likely a salty ocean. They knew it was not possible “that the ocean was evaporating through the ice shell to create water vapor,” the report said.
Ganymede, which is named for a cupbearer to the ancient Greek gods, is not only the largest natural satellite in our solar system, but it is also the only moon to have a magnetic field. This generates “auroras that glow around the moon’s north and south poles,” the report explained. The researchers’ desire to reportedly learn more about Ganymede “as a potential habitat for life” will be bolstered when the European Space Agency’s JUICE mission, or when Jupiter Icy Moons Explorer launches in 2022. Upon its arrival at Jupiter in 2029, it will spend three years observing the giant planet and its three largest moons, which will include Ganymede.
The differences seen in the ultraviolet images taken by Hubble can be explained, and are caused by significant variations in Ganymede’s surface temperature over the course of a day. Researchers found “around noon at the moon’s equator, it becomes warm enough for the icy surface to sublimate, or release small amounts of water molecules.” Even though Ganymede’s ice shell is as hard as a rock, a stream of charged particles from the sun is enough to erode and release water vapor, the study said. NASA’s Juno mission, which has been observing Jupiter and its moons since 2016, recently took the first close-up images of Ganymede in two decades, CNN noted.
There is an explanation. The first ultraviolet images of Ganymede, revealing the auroral bands, were captured by Hubble in 1998. Researchers initially believed these auroras were the result of the pure oxygen atmosphere, which was first detected in 1996 using the same telescope. Only, “some of the features couldn’t be explained and even appeared slightly different from one another,” researchers noted.
By understanding more about Ganymede, researchers can increase their knowledge about how “gas giants” like Jupiter and their moons “form and evolve over time.” Whether the icy moons throughout our solar system, are habitable environments where life can exist. What can be learned from Ganymede?
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- Headline: Hubble Detects Water Vapor Around Ganymede, Jupiter’s Largest Moon, Study Finds
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