Twenty - two years ago , the Galileo spacecraft made its first flyby of Ganymede , Jupiter ’s largest lunar month . Scientists with NASA have taken a raw smell at the information collected during that historical clash , providing tantalizing new details about this strange supernal aim , its unique magnetic shell , and its remarkably bright sunrise .
We do n’t speak very much about Ganymede , but it ’s actually a really coolheaded moon . Not only is it Jupiter ’s gravid moonlight , it ’s the largest moon in the Solar System , and the ninth large physical object in eye socket around the Sun . Its diam is about 3,200 miles ( 5,200 km ) in duration , making it slightly larger than Mercury . Fascinatingly , it sport a subsurface ocean , withpotentially more piddle stored within itthan exists on Earth ’s airfoil .
On June 26 , 1996 , NASA ’s Galileo spacecraft made the first of six flybys around the lunation , and it made a rather surprising find : Ganymede has a magnetic buckler , a feature also known as a magnetosphere . This caught astronomers off safety gadget , as they antecedently thought only planets , such as Earth , Mars , and Jupiter , are subject of generating and support magnetic field of view . But there it was , Ganymede with its swoon magnetosphere nestled within Jupiter ’s much larger , and far more powerful , charismatic shield . The go account for this unexpected feature is that it ’s being generated by convection within the moon ’s liquified smoothing iron core .
Studying magnetospheres , whether it ’s the one around our planet or the one around some distant Sun Myung Moon , is significant . It ’s very unbelievable that Ganymede can host life sentence , but by con more about this moonshine ’s protective charismatic house of cards we stand to memorize more about this critically important physical phenomenon . Without a magnetosphere , Earth would likely be a unimaginative rock and roll , with the Sun ’s damaging radiation forever bombarding the Earth’s surface . It ’s safe to say that without a magnetosphere , the chances for aliveness are slim to none . So by studying the magnetospheres within our Solar System , we could learn about the environs around other potentially inhabitable cosmos elsewhere in the galaxy .
Among Galileo ’s many pawn was the Plasma Subsystem ( PLS ) , which value the denseness , temperature , and direction of plasm ( ie excited , electrically charge gas ) flowing around Ganymede . The space vehicle diligently collected this information during the 1996 flyby , but the data was never published . Astudyled by Glyn Collinson from NASA ’s Goddard Space Flight Center , put out this week in Geophysical Research Letters , has taken a fresh look at this old data , extend raw details about Ganymede ’s unique magnetosphere .
The new findings are painting a portrait of a truly alien world .
Normally , magnetospheres are forged by the force per unit area of the Sun ’s incoming tip , but in this fount , it ’s being shaped by easy - moving plasm waft around the Jovian system . This gives Ganymede ’s magnetosphere a strange , trumpet - like shape that extends forward of the moon in the guidance of its orbit .
At the same time , Jupiter ’s high-pitched - Department of Energy plasma subatomic particle are raining down on the polar regions of Ganymede ’s frozen surface , stimulate extremely charge , water - ground particles to careen back into space .
“ There are these particles fly out from the polar regions , and they can separate us something about Ganymede ’s atmosphere , which is very thin , ” read Bill Paterson , a atomic number 27 - writer of the study at NASA Goddard , in a program line . “ It can also tell us about how Ganymede ’s auroras form . ”
Indeed , Ganymede features sunup similar to Earth ’s northern and southern lights . But unlike on Earth , where our auroras are produced by incoming solar atom , the auroras on Ganymede are being generated by the blood plasma surrounding Jupiter . Using data antecedently collect by the Hubble Space Telescope , and by corroborate it with Galileo ’s PLS data , the NASA scientist were able to qualify and pinpoint the localization of the auroras on Ganymede . Further research could explain why Ganymede ’s auroras are so freakishly bright , a unknown watching given the impuissance of the moon ’s magnetosphere .
Excitingly , this research is n’t over . Future analysis of PLS data point from Galileo ’s historic encounter could learn us about thesubsurface sea antecedently determined to existwithin the moon . It ’s thought that this subterranean ocean , through the force of clash , is creating a secondary magnetised field that ’s interacting with Jupiter ’s field .
Ganymede does n’t steal the spotlight like many of the Solar System ’s other moons , but that ’s poised to switch . In 2022 , the European Space Agency will launch JUICE — JUpiter ’s ICy Moons Explorer — an interplanetary space vehicle that ’s schedule to see Europa , Callisto , and Ganymede in the early 2030s .
[ Geophysical Research Letters ]
GanymedeJupiterMagnetic FieldsmoonsNASAScience
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