The giant moon Ganymede may have an underground ocean with more water than the entire earth. Now scientists have also discovered traces of water in the lunar atmosphere.
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It is very cold on the Jupiter moon Ganymede, so liquid water is only found far below the surface, space scientists believe.
But now scientists believe they have discovered traces of water in the lunar atmosphere. The discovery was made using the Hubble Space Telescope, which orbits the earth about 600 kilometers in the air.
Ganymede is the largest of Jupiter’s 79 moons. It is less than half the size of Earth, but larger than the planet Mercury. Ganymede could almost be a planet of its own, but it is not, since it orbits Jupiter.
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The new results are published in the journal Nature Astronomy.
As early as 1998, Hubble took the first ultraviolet images of Ganymede. Then scientists could see that the moon had a magnetic field similar to that of the earth, and they also saw signs of oxygen in the lunar atmosphere.
Only moon with magnetic field
With a diameter of 5268 kilometers, the Jupiter moon Ganymede is not only the largest in the solar system, but also the only one with its own magnetic field.
This magnetic field creates polar light, ie bands of electrified, luminous gas in areas at the moon’s north and south poles – something similar to the northern lights and the southern lights here on earth.
Scientists believe that there is an ocean on the moon. The ocean is 100 kilometers deep, ten times deeper than the earth’s ocean, and lies beneath a 150 kilometer crust of mainly ice. This may be more water than the total amount on the earth’s surface.
(Source: Erik Tandberg’s blog on forskning.no)
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But after several analyzes and many years of work, the researchers now find that it was not only oxygen they had discovered, but traces of water.
– It was difficult measurements and it was surprising that our method worked, but we expected that there would be water vapor there, says Kurt Retherford, professor at the American Southwest Research Institute and ESA researcher, to magasinet Popular Science. He is one of the researchers behind the new study.
More water than on earth
Ganymede’s surface consists mostly of hard ice. But far below the shell, there may be water, more water than there is on Earth, according to NASA.
I In 2015, researchers found signs that there is a huge sea of salt water below the surface.
The new discovery shows that it can get so hot around the equator on the moon that a bit of ice rises in the atmosphere.
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Next year, the European Space Agency (ESA) will send a space probe to Jupiter. Probe JUICE (Jupiter Icy Moon Explorer) will examine both the gas giant Jupiter and the three moons Europa, Ganymede and Callisto.
– Our results can provide the JUICE team with valuable information that can be used to optimize the use of the spacecraft, says Lorenz Roth at the Royal Institute of Technology in Stockholm, who is the main researcher behind the new study, in a press release.
Earlier this year, the spacecraft Juno flew past Ganymede. It took impressive pictures showing parts of the moon’s surface in detail. Craters, grooves and light and dark fields are visible. Les more in this case on ung.forskning.no.
Reference:
Lorenz Roth m.fl: A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations, Nature Astronomy, juli 20201
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