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astronomers using archival data from

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nasa's hubble space telescope found

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evidence of water vapor in the thin

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atmosphere of jupiter's moon ganymede

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ganymede is the largest moon in our

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solar system larger than mercury and

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pluto and three-quarters the size of

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mars

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it's an ice-covered world that may hold

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more water than all of earth's oceans

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combined

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but unlike earth ganymede's oceans are

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below its 100-mile thick icy crust

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ultraviolet images taken in 1998 and

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2010 using hubble's space telescope

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imaging spectrograph revealed bands of

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charged particles at ganymede similar to

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earth's polar auroral ovals the regions

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that give us our northern and southern

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lights but the two observations revealed

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differences in ganymede's auroral bands

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over time the researchers thought these

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differences were due to the presence of

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atomic oxygen or single oxygen atoms in

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ganymede's atmosphere atomic oxygen

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affects one of the wavelengths of

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ultraviolet light the scientists were

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looking at

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in 2018 researchers used hubble's cosmic

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origin spectrograph to measure the

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amount of atomic oxygen in ganymede's

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atmosphere they compared the 1998 2010

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and 2018 data to their surprise the 2018

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data revealed hardly any atomic oxygen

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in ganymede's atmosphere there had to be

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another explanation for the differences

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in the aurora images ganymede's surface

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temperature varies widely throughout the

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day and around noon near its equator it

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may get warm enough for surface ice to

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release water molecules

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instead of melting and forming liquid

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water the icy surface warms and changes

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from a solid directly to a gas a process

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called sublimation

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looking back at the original images the

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team discovered the differences they

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observed in ganymede's auroral bands are

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related to where water vapor would be

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expected in the moon's atmosphere

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understanding the jovian system and

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unraveling its history from its origins

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to the possible emergence of habitable

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environments will provide us with a

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better understanding of how gas giant

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planets and their satellites form and

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evolve

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along with learning more about jupiter

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and its mysterious moon ganymede this

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exciting new discovery has brought us