Jupiter is a planet of records . It is the big in the Solar System , the most monolithic , and the one with the strongest magnetic field . It also has the most number of moons . And now a dozen new ones have just been discovered .
Astronomers were n’t in reality looking for young moons around the gas giant star . Instead , they were looking for Planet Nine , a yet - to - be - confirm object that might orbit the Sun way beyond the celestial orbit of Neptune . Jupiter was near the spot they were look for this object and they just so happened to detect the subtle social movement of these new petite moons .
“ Jupiter just happened to be in the sky near the lookup fields where we were looking for passing distant solar scheme objects , so we were serendipitously capable to await for young moons around Jupiter while at the same time depend for planet at the outer boundary of our solar system , ” squad leader Scott Sheppard , from Carnegie Institution for Science , say in astatement .
Sheppard spotted the Sun Myung Moon first in the natural spring of 2017 , but it shoot a whole yr and several observation to all characterise the arena of the new moons . All of them revolve the planet further out than the four Galilean satellites ( Io , Europa , Ganymede , and Callisto ) . Two moons are part of the prograde grouping of lunation , the one that orb Jupiter in the same direction as it rotate . This group is believe to be the remains of a large moon that damp apart . These moons take a little less than an Earth year to move around around the satellite .
The other 10 moons are part of a further out group known as the retrograde . Nine of them orbit Jupiter in a retrograde style ( against its rotation ) , but one is weird and goes around prograde . This singular synodic month orbits Jupiter in about 1.5 years and is tiny .
“ Our other discovery is a real oddball and has an sphere like no other known Jovian moon , ” Sheppard explained . “ It ’s also likely Jupiter ’s smallest known moon , being less than one kilometer in diam . ”
The squad nicknamed it Valetudo , after the papist goddess of health and hygienics and big - granddaughter of Jupiter . All the other new moons are fairly minor as well , between 1 and 3 kilometers ( 0.6 and 1.9 mi ) in diam .
Studying these moon set aside researcher to get a undecomposed understanding of the formation of the Solar System . For exemplar , these objects are strongly determine by gas and dust , so their constitution must have been subsequent , otherwise they would have lose speed due to friction and would have fallen into Jupiter .
