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NASA ’s Juno spacecraft has spotted the elusive fifth synodic month of Jupiter transiting the jumbo planet ’s Great Red Spot , giving uranologist a rarified scene of this little but challenging rude orbiter .
Jupiter ’s most famous moons are its four Galilean satellites : Io , Europa , Ganymedeand Callisto , each of which is several thousand klick all-embracing . Jupiter ’s 5th moon to be discovered , and the fifth - large of the planet ’s 95 recognise moons , is Amalthea . It was ground in 1892 by Edward Emerson Barnard , an American uranologist who was an striking optic perceiver . He also key Barnard ’s Star , as well as a host of dark nebula .
Amalthea, seen in two images of Jupiter captured by NASA’s Juno spacecraft on March 7, 2024.
Despite being Jupiter ’s fifth - largest moon , Amalthea has fairly pocket-size dimension . on an irregular basis shaped like a potato , its long axis stretch just 155 international nautical mile ( 250 kilometers ) , and its narrowest period spans a bare 79 miles ( 128 klick ) . Gravity measurements by NASA ’s Galileo spacecraft in the former 2000s deduced that Amalthea is little more than a broadly held together detritus good deal rather than solid rock .
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Now , Junohas espy Amalthea for the first time , during the spacecraft ’s 59th close flyby of Jupiter , which occur on March 7 of this yr . Juno ’s orbit is a long , looping one around the gun giant , with a close encounter ( referred to as a " perijove " ) every 53 Earth day ; it was meant to move into a inadequate orbit , but a misfiring engine cause by incorrect valve means that Juno is rest where it is for the duration .
Amalthea, seen in two images of Jupiter captured by NASA’s Juno spacecraft on March 7, 2024.
Juno spotted Amalthea as a tiny black speck congeal first against one of Jupiter ’s ruddy , dark cloud belt and then transiting theGreat Red Spotitself . The exfoliation is unbelievable ; the Great Red Spot is a vast anticyclonic tempest that ’s currently 7,767 nautical mile ( 12,500 kilometer ) across , while petite Amalthea is pictured 112,500 international mile ( 181,000 km ) above Jupiter ’s swarm height .
In fact , Amalthea has the third - unforesightful compass of any of Jupiter ’s moons , revolving around the elephantine planet every 0.5 Earth days on the inside racecourse relative to volcanic Io ’s orbit . It shines at magnitude +14 , and with it being so stuffy to the glare of Jupiter , Barnard did an unbelievable problem discovering it . Suffice it to say , Juno ’s project is much easier .
Close - up images of Amalthea by NASA’sVoyager 1andVoyager 2probes and the Galileo space vehicle show several lustrous spots and craters on the modest synodic month , as well as how cryptically red its surface is . In fact , Amalthea is the ruddy body in thesolar system . The identity of this red coating remains strange , but one possibility is that it is atomic number 16 that has been belched out by Io ’s volcano and made its way across space to neighboring Amalthea .
Amalthea, seen in two images of Jupiter captured by NASA’s Juno spacecraft on March 7, 2024.
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Our best images of Amalthea so far come from NASA’s Galileo spacecraft. These four images show the different sides of the tiny moon.
There ’s an even deeper mystery with Amalthea , in that it emit a little more heat than it encounter from the sun . Where is a moon as small as Amalthea is getting this surplus vigor from ? Several explanations have been put forward , and the verity could be one or a combination of them .
For example , Amalthea is bathed in heat both radiate and reflected by Jupiter , while the vise - like grip of Jupiter ’s gravity could engender tidal stresses within Amalthea , generating heat . Then there ’s Jupiter ’s thumping magnetised athletic field , which generates a magnetic house of cards that is the secondly - prominent structure in the solar system of rules after the Lord’s Day ’s own magnetic house of cards , the heliosphere . Amalthea , on its poor orbit , is deeply ensconce within Jupiter ’s magnetosphere , in a neighborhood where there are radiation belt of charged particles that can pelt Amalthea ’s surface , imparting DOE . last , the magnetosphere may even be able to induce electric current within Amalthea ’s Congress of Racial Equality that produce the superfluous fondness .
Whatever the answer , it adds to the allure of this fifth synodic month , often forgotten about next to its renowned large sib , but with a narrative that can be just as tantalizing .
Originally published on Space.com
