Discovering Jupiter

8/7/2019 Discovering Jupiter

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the jovian BeetSpacecraft Launch AccomplishmentsPiol/eer 10 3/3/72 Flybl'. First spacecrafl. to the outerU.s. planets. Passed within 130,354 killof Jupiter ( 12/3/73). Imagedcloudtops and moons, measuredJovian atmosphere, magnetic fie ld,interior structure, and masses of NGa lilean satellite. r--N0Piol/eer J1 4/6/73 Flvbv /0 Jupi/er and Sa/lim. Sec- r--U.S. ond spacecra ft to the outer plan- Iets. Passed within 43,000 km of '"0-Jupiter (12/2/74). First images of Zpo lar regions. New flow featuresobserved around Great Red pot.Deep penetration and study ofra-diation belts. Mea ured mass ofCallisto.Voyager I 9/5/77 Fll'bv. Passed within 350,000 km ex:U.S. of JLJpiter (3/79). Discovered a wfaint ring, three moons. Detailed ~ imagery of atmospheric phenom- ....ena, Gali lean sate ll ite surfaces, 0..::>Europa fract ured ice mantle, ..,grooved te rrain on Ganymede, ac-


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jupiter: king of p ~ a n e t s Jupi ter, named afte r the king of the Roman gods, reign

supreme among the nine planetsofour so lar system, ri va ling th eSun in its grand em. Giant Jupiter co ntains two -thirds of theplanetalY ma sor the so lar system. In co mpos ition it resembl esa small star. Its interior pressure may rea ch 100 milli on tim esthe surface pressurc on Earth. Jupiter' s ma gnetic fi eld isimm ense, evcn in propOlti on to the size of th e planet, stretchin gmi ll ions o f mi les into th e so lar system. [f the magnetic fieldwere visible , it wou ld ri va l the apparent size of our Moon.Elec trica l activity in Jupiter is so strong that it pours bi ll ion s ofwa lts into Ealth's own ma gnetic fi eld evelYday . No planet hasgrea ter influence on its neighb ors.

Endowed with 16 kn own moo ns, a rin g system, and animmense, compl ex atm os ph ere. Jupiter is the inn erm os t of th e4 giant planets (the oth ers are Saturn , Uranus, and Ne ptune), andclea rly the mo stdynami c. Its atm os ph ere bri stles with lightningand swirls with hu ge storm systems, including the Great RedSp ot, a sto rm that ha s persisted for at leastIOO- and perhapsas long a 300- years.With its dynami sm, huge energy output,and entourage of sa tell ites, Jupiter is inmany way like a small sun , and the

atmos ph eres today. Jupi te r, the inn crm o t of"grew" the largest atm os ph ere. In fact, the facwe see is rea ll y just the top of its atm o ph ere.inside is even more intriguin g.

Jupiter' s massive atm os ph ere creates tremeas yo u mo ve closer to th e cc nter of th e planet.inside th e atm osph ere are subjcct to ex trcmIcading to exo tic chemi stry. Fo r cxampl e, reason to be lieve th at th e inn er laye rs o fJup it er ' s atm osphere, under the pressure ofabove, may have form ed into a pl anet-enc iwhat is ca lled liquid metallic hydrogen. Nocean, not exactl y atm osphere, this laye r of hha ve propert ies th at stretch our understandinIn stead of th e simple, free -m ov in g and lobehav ior of gaseous hydrogen. liquid metallistrange matrix capable of conducting hu gc

rents. The pers istent rimp ro babl y stro ng mag npi te r co uld both emanateof metallic liquid. So mcrize that benea th thi s la


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),lDissions of discoverylPioneer 11 , flew by JuSaturn, and provided evimage ry and measureour fi rstclose-up look apolar reg ions. ThenSeptember 1977, NAStwo Voyager spacecralar sys tem. The Voycounters w ith Jupiterstartling, beautiful imaof the planets, revea lifea tures neve r beforemulticolored turbu lencGreat Red Spot. Ri ssp inning eddies formesuggesting a strong sobling up from within t

Jupiter is one of the planets visibl e tothe naked eye, and its path through thenight sky has been traced for thousandsof years. [n J61O, the Italian as tronomerGa li leo Galilei discovered four largemoons-Io , Europa, Ga nymede, andCa ll isto (known as the Ga li lean sa telli tes)--rbiting Jupiter. This was oneofthe ear l ies tastronom ica l discoveries madewith a telescope. It fueled the controversia l argument of the tim e th at theSun andnot the Ea rth was the center of the so larsys tem. [n the centuries since then, aste lescopes improved, Jupiter becam eknown primariIy for its size and the Grea tRed Spot, which was imag ined to be anisla nd in a Jov ian sea . A s Earth-basedast ronomy continued to improve, wecame to rea li ze that the few fu zzy " surface" fea tures we could see were con-

Jupiter and the Galilean satelliles-/o, Europa,Gallymede, and Callisto ..

Th e Voyager imagesure of so many small dJov ian dynamics were

stantly changing in position , size, and pl ex than previous ly im


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unanswered q u ~ s t i o n s ,. ,. \There is much to learn aboutJupiter. Wedo not yet know the

detai ls of the inner chemistry and phys ics of the planet. A nunderstanding of the state of the planet today wi ll reveal muchabout its formation, and about the formation of the so lar systemitself. We have on ly ave ry bas ic understand ing ofwhat isgo ingon in Jupiter 's atmosphere , its chemistry, circul ations, andinteraction with the core beneath. Understanding Jupiter 'satmosphere w il l no doubt shed l ight on the behavior of our ownatmosphere, which in ome ways resembles, on a small sca le,that of Jupiter. We also need to know more about Jupiter 'sinteraction with its moons, and about the moons themse lves.


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Discovering Jupiter