SOLAR CLOSE-UP by Monica Young NASA's Parker

SOLAR CLOSE-UP by Monica Young To Touch the Sun

NASA’s Parker Solar Probe is on a record- breaking journey to study our nearest star.

he launch of the Delta IV Heavy sounded of fi re By the time this issue reaches newsstands, Parker and thunder. The rocket’s vibrations rumbled will already have swung around the Sun six times, with T over the team of scientists and engineers stand- another 18 passes planned, gradually approaching the ing miles away in the early hours of August 12, 2018, Sun. During its fi nal three orbits — starting December as they watched the rocket carrying NASA’s Parker 24, 2024 —the spacecraft will pass within 6.2 million Solar Probe lumber into the sky. kilometers (3.8 million miles, or about 9 solar radii) Team member Kelly Korreck (Center for Astrophys- of the seething gases in the photosphere. At its closest, ics, Harvard & Smithsonian) was tense. As the head of Parker will be traveling at 190 km/s (430,000 mph), science operations for one of the mission’s instrument fast enough to travel from New York to Tokyo in under suites, she knew what to listen for from pre-launch a minute — and faster than any other mission before it. vibrational testing — when one particular instrument Designed, built, and operated by the Johns Hopkins mock-up had begun to rock violently. Applied Physics Lab, the spacecraft carries four inde- “In testing, we heard the Solar Probe Cup rattle, just pendently developed instruments to this unexplored ‘djr-djr-djr’ at one point in time when it hit a certain territory. Mostly shielded behind 11.4 centimeters (4.5 frequency,” Korreck says. “As I was listening to the inches) of carbon composite, the detectors measure elec- frequency of the rocket taking off, I was listening like, tric and magnetic fi elds, plasma properties, and particle ‘Oh here she is, oh my goodness, she’s rattling right energies, as well as image the corona and solar wind. now, she’s rattling!’” “The spacecraft itself is just crammed tight,” says Russell Relief came soon enough. Within 45 minutes, the Howard (Naval Research Laboratory), principal investi- spacecraft sent a signal indicating it had reached its gator of the WISPR camera. expected trajectory; over the following weeks, its After decades of studying the Sun from afar, Parker’s instruments switched on one by one. “That thing is various detectors are fi nally giving scientists a close- actually going to go into the atmosphere of a star,” up look at our star — a chance to “touch” the Sun and Korreck recalls thinking. “It’s an amazing feeling.” pierce its mysteries.

ART1_Parker.indd 20 8/17/20 10:44 AM ART1_Parker.indd 21 NOT TO SCALE TO NOT ©2020 Sky&Telescope. AllRights Reserved. sunward. Solar Probe the Parker air, carrying lifts intothe Heavy rocket ance DeltaIV Launch Alli- The United u LAUNCH and tastethenascentsolar corona asit’s beingheated skyandtelescope.org Parker willswiminthehot wind asitsparticlesare being accelerated. • N OVEMBER 2020 8/17/20 10:45 AM 21

PARKER ARTIST’S CONCEPT: NASA / JOHNS HOPKINS APL / STEVE GRIBBEN; LAUNCH: BILL INGALLS / NASA ART1_Parker.indd 22 22 Solar Close-up it’s scientifi —but poetic is astar touch can a spacecraft that notion The theSun’sInside Atmosphere NOVEMBER 2020 q scientist AnthonyCaseprepares theSolarProbe Cupbefore itsintegrationontothespacecraft. Solar Probe Cupononeside.Particlesfrom anion gun(wrappedinfoilandpointeddownatthechamber)simulatedsolarwind. the Sun.Speciallensesoffusedsilicaconcentratedanddirected thelightintoa vacuumchamber(theglowingholeseenatleft), illuminatingthe around in the corona, suggests Solar Probe Cup instrument Cup instrument Probe Solar suggests corona, the in around measure. we ofwhat physics the controlling clearly is Sun the that enough —close star our to closer alot get to have we realized, astronomers origins, their Todecades. understand six for than more debated hotly been have sources their established, nowwell are wind solar speedy the and corona second. every Lake Utah’s Salt Great of mass the loses Sun the We that nowknow wind. solar confi 2probe Mariner the later, years four Just timing: good be outto It turned scientifi the he overruled fi but hecouldn’t idea, the like didn’t Chandrasekhar Subrahmanyan editor published. didn’t get italmost that ideas fl escape, would particles charged —the herealized Sun, the to bound stay wouldn’t plasma ahot Such implications. full the down wrote 1958 in and Parker Eugene ofdegrees, millions to heated aplasma in exist only can electrons many that missing Atoms such). as them identify to 73 years (though ittook atoms iron ionized 13-times by emitted light recorded that eclipse solar atmosphere. outer diffuse the into and photosphere the beyond well extends dominance Sun’s the . Nevertheless, or photosphere Sun’s surface, visible the represents halo glowing to ball searing from transition The corona. solar ofthe glow softer the itreveals Sun, ing burn- ofthe glare the blocks Moon the When ofsorts. edge an seen long have eclipses solar oftotal butwitnesses surface, INGENUITY &IMAX Think of a big prominence rising off the Sun and looping looping and Sun the off rising prominence ofabig Think multi-million-degree ofthe existence the while However, prevailing to contrary so was idea Parker’s time, the At 1869 the total during corona of the observations It was nosolid has Sun our is that ofplasma ball churning The cally defi cally owing outward in a supersonic solar wind. wind. solar asupersonic in outward owing nd anything wrong with Parker’s math, so so math, Parker’s with wrong nd anything SKY &TELESCOPE •SKY ned, too. ned, Left: Theteamcombinedthelightfrom four IMAX-likeprojectors tosimulatethelightandheatthatwouldbecomingfrom rmed the existence of Parker’s theorized theorized ofParker’s existence the rmed c reviewers and published the paper. the published and c reviewers ©2020 Sky&Telescope. AllRights Reserved.

Astrophysical Journal Astrophysical

p purple; green showsitsfuture path. 9 solarradii.Parker’s pasttrajectoryandcurrent positionare shownin from thevisiblesurface.Thelastthree periheliawilltakeParkerwithin The fi rstperiheliontookthespacecraftwithin36times Sun’s radius boundary between the Sun and its outfl its and Sun the between boundary the So changing. constantly are Sun the near conditions fi Magnetic radius Alfvén the call tists one scien- there’s atransition, says, Case between, in point it’s Sun; fl ofthe part nolonger is wind solar ofthe plasma magnetized the Earth, Butat Sun. the to “belongs” still prominence the a sense, fi magnetic the follows prominence the in plasma the because to, it—has with rotates prominence the rotates, Sun the As Smithsonian). & Harvard (Center for Astrophysics, Case Anthony scientist APPROACH The Alfvén radius isn’t any more solid than the Sun is. is. Sun the than solid more isn’t any radius Alfvén The

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PARKER ORBITS: GREGG DINDERMAN / S&T; SOURCE: NASA / JOHNS HOPKINS APL; IMAX SETUP: LEVI HUTMACHER / MICHIGAN ENGINEERING, COMMUNICATIONS & MARKETING; SOLAR PROBE CUP: ANDREW WANG / ANDREWTAKESPHOTOS.COM ART1_Parker.indd 23 PARKER INSTRUMENTS: NASA / JOHNS HOPKINS APL (2); HEAT SHIELD: NASA / JOHNS HOPKINS APL / ED WHITMAN; PARKER IN ROCKET FAIRING: NASA / JOHNS HOPKINS APL / ED WHITMAN its particles are being accelerated. being are particles its as wind solar nascent the taste and heated it’s being as corona hot the in swim will Parker radius, Alfvén the Within done. ever has nospacecraft something boundary, this inside slip to is Probe Solar Parker radius.” asolar “It’s plus orminus explains. a mile,” Korreck plus orminus “It’s just not bumpy, too. and dynamic q siderefl shield’s sunward-facing the on coating oxide aluminum ultra-white it’s 97% An empty. lightweight so that’s foam ofcarbon slice athick sandwich material carbon ofagraphite-like layers Two thin create. to adecade than more took that engineering ofthermal piece amaster- shield, ofaheat shelter the behind from surements mea- their take therefore instruments ofthe Most on Earth. lava any 1,400°C than (2,500°F) approaching —hotter tures tempera- reach would Parker Unshielded, atEarth. receive we water. ofhot aglass in than rather oven ahot in hand your sticking like is difference The itself. sunlight the from comes feel does probe the heat The Parker. to heat transfer to sparse too they’re and particles, plasma’s ofthe motions the describes number that degrees, amillion than more is corona ofthe temperature the While think. one might as hot as doesn’t feel environment the that is news good The furnace. stellar the to approaches close its fi itmust though, ofthat, doany can Parker Before Taking theHeat that theydon’t interact. coating ofaluminumoxide.Athintungstenlayerseparatesthetwo so components: alightcarbonfoamthat’s mostly spaceandabrightwhite PARKER’S SUNSCREEN A primary goal for the forthe goal A primary Still, radiational heat at closest approach is 500 times what what times 500 is approach atclosest heat radiational Still, The heatshieldconsistsoftwomain protection Thermal system ects most of the light and and light ofthe most ects ©2020 Sky&Telescope. AllRights Reserved. Solar array array Solar wings (2) wings rst survive survive rst Solar Probe Cup Probe Solar SWEAP cooling system array Solar High gain antenna gain High SPAN-B SWEAP that facesthedirection ofmotion. Parker SolarProbe. Theviewatrightshowsthesideofspacecraft rocket provided thenecessarylifttobringParkercloseSun. was smallcompared towhataDeltaIVHeavyusuallycarries,the half ofthe19.1-meter-tall (62.7-foot-tall)fairing.Although theprobe q p STANDING TALL ALL ABOARD skyandtelescope.org lightl imager CoronalC white- WISPRWI These viewsshowtheinstrumentsaboard the i gh o r The ParkerSolarProbe lookssmallinsideone Electric fi Electric FIELDS eld antennas (4) antennas eld particle sensors particle high-energy and Low- IS • N OVEMBER 2020 SPAN-A+ SWEAP IS Magnetometers (3) FIELDS 8/17/20 10:45 AM 23 ART1_Parker.indd 24 24 To theSun, Via Venus NOVEMBER 2020 and evenexoplanets. tect it—aquestion relevant to otherworldssuchasTitan to maintainitsthickshroud withoutamagneticfi eld to pro- extrapolate backintimetounderstand howVenus wasable data are nowrevealing howandwhy. Scientists canthen typically managestoescape, Curryadds,andParker’s magnetic reconnection works.” shocks form,howthemagnetotailstructure works,how croscale physicsthatexplainalotofhowthingslikebow explored outsideEarth,notevenatMars,”Currysays.“Mi- promising. “We’re fi ndingthingsthathaveneverbeen the initialresults from thefi rsttwo Venus encountersare that fl owsaround thismagneticallydeadworld. sphere aswellthefi eldsinducedbythecharged plasma planetary scientistsanopportunitytoexplore itsalienatmo- the lastthree decades(S&T: Sept.2018,p.14).Parkergives pitable Venus hasbeenrelatively neglectedbyspacecraft in the nextone. tightly coupled,sothatonefl ybysetsthespacecraftupfor works becausethebrakingmaneuversaround Venus are Venus ratherthanonebyJupitercoulddothetrick.Itonly another waytotheSun.Guorealized thatseven swings by spoken forbyothermissions. and NASA’s limitedsupplyofplutonium-238wasalready the question.AJupiterfl ybyusually requires nuclearpower, so muchspeed—aswingaround Jupiter—was outof required toreach Marsandtwicethattoreach Pluto!” energy required toreach theSunismore than50times that Applied PhysicsLaboratory).“Thelaunch Yanping Guo (JohnsHopkinsUniversity takes more energy, saysmissiondesigner Slowing thatmomentumcounterintuitively its orbitalspeedof30km/s(66,500mph). as anyspacecraftleavingEarthinherits than leavingthesolarsystemaltogether, Approaching theSuntakesmore energy Previous missionshadquantifi edhowmuchatmosphere Berkeley)says Shannon Curry(UniversityofCalifornia, The fl ybysserveasmore thanatrajectoryassist.Inhos- For Parkertoevenbegindevelopment,itwouldneed When missionplanningbegan,thebestoptionforlosing SKY &TELESCOPE •SKY ©2020 Sky&Telescope. AllRights Reserved. FLYBY p toward theSun. on itsjourney Solar Probe boost theParker from Venus gravity assists VENUS Seven pass around theSun—alongwiththousands ofmagneticswitchbacks. known ascoronal holes.Parkerencountered sucharegion duringitsfi sent regions where magneticfi eldlinesescapeintointerplanetaryspace, represents extreme ultravioletemission;whiteareas onthesurface repre- fi gurationfortheSunduring Parker’s fi rstperihelion.ThecoloroftheSun extend beyond the shield easily withstand the heat. But these Butthese heat. the withstand easily shield the beyond extend up. keep couldn’t conditioning air building’s the Sometimes silica. of fused lenses special using chamber avacuum into projectors like IMAX- offour light the concentrated team the Sun, the near experience would SPC the that heat the and light the late temperatures. atextreme cracking from them fi after electronics, the insulate to sapphire lab-made used also team The cup. ofthe bulk forthe zirconium and titanium nozzles. orrocket reactors nuclear in used those like metals, refractory are remaining options only The &Smithsonian). Harvard (Center for Astrophysics, Bergner Henry engineer gone,” long is structural says aluminum all melt, steels “all 1,600°C, ofsome temperatures testing At titanium. unalloyed and steel ofstainless plates deformed wall: on the hang still “mistakes” long. The too stove on the left apan like smelled lab the tests, material During curtain. awelding behind sometimes error, and trial took Sun the shield. heat the beyond extend also suite, ment fi electric the measure help that antennas whip four And Sun. the toward directly receptacle particle-collecting its point to shield heat the outside hangs instruments, (SWEAP) Protons and Alphas, Cup (SPC), Electrons, Wind Probe Solar one ofthe Solar The it. beyond extend that for two except temperature, gray. turning and foam carbon the with interacting afi heat; p guring out how to grow the crystals in a way that keeps keeps that away in crystals the grow outhowto guring CORONAL WINDOW For the FIELDS instruments, the whip antennas that that antennas whip the instruments, FIELDS the For To ingenuity. simu- some required instrument the Testing with alloyed on molybdenum decided team the end, the In to close so function could that instruments Developing room atroughly instruments most keeps shield The ne layer of tungsten keeps the aluminum oxide from from oxide aluminum the keeps oftungsten ne layer eld, part of the FIELDS electromagnetic instru- electromagnetic FIELDS ofthe part eld, Switchbacks Parker Solar Probe Solar Parker This schematicshowsapossible magnetic con- Coronal hole rst 8/17/20 10:45 AM

PARKER’S VENUS FLYBY: NASA / JOHNS HOPKINS APL / STEVE GRIBBEN; MAGNETIC FIELD SCHEMATIC: UNIVERSITY OF CALIFORNIA, BERKELEY; SPACECRAFT IMAGE: NASA / JOHNS HOPKINS APL ART1_Parker.indd 25 PARKER FLYING THROUGH SOLAR WIND: NASA; SWITCHBACKS ILLUSTRATION: NASA GODDARD / CIL / ADRIANA MANRIQUE GUTIERREZ; INTERCHANGE RECONNECTION: GREGG DINDERMAN / S&T; SOURCE: JUSTIN KASPER / LEVI HUTMACHER / UNIVERSITY OF MICHIGAN ENGINEERING care of herself now.” ofherself care shield’s “She’s shadow. says. taking “She’s adult,” an Korreck heat the in instruments its all keep spacecraft the help sors sen- light and trackers star and panels, solar its fold back can spacecraft the heat, rising to response In sion-making. says. atall,” Bergner thing this with we’re communicating not that mission a bitofthe fl spacecraft the Sun, the by passes close searingly its during so for instrumentation, required that’s power takes Earth with Communicating launched. ever ofMichigan). (University Kasper Justin investigator principal SWEAP says temperature,” own its effi panels the —keeping space into itback radiates then heat, absorbs water the system, vascular our Like radiators. four into then fl which water, ofdeionized agallon about with cool keep They Sun’s the to light. exposed partially reasons, for obvious approach. at closest warm them keep to heaters need actually they effective, so is heat the from protection Their spacecraft. the behind shadow investigator. principal Berkeley), FIELDS of California, fl heat the chokes bitofshadow, itjust little any behind tube you putthat they fi that thin so are walls tubes’ the Fortunately, spacecraft. ature fi electric the sure mea- help which niobium, ofreactor-grade tubes hollow long, Parker’s initialfl nomenon, switchbacks surprisedastronomers intheirabundance during that Parkerobservesasitfl iesthrough the structure. Whileaknownphe- magnetic fi eldlineandtheaccompanyingburst of solarwindparticles switchback mightlooklike,depicting boththeS-shapecurveto p ows through small channels embedded in the panels and and panels the in embedded channels small through ows SWITCHBACK A variety of sensors and controls aids Parker in its deci- its in Parker aids controls and ofsensors A variety spacecraft autonomous most one ofthe is Parker Indeed, itregulates animal, awarm-blooded like is spacecraft “The butare, shield heat the behind also are panels solar The the in hide FIELDS and ofSWEAP instruments other The x their own problem: They barely conduct heat. “Once “Once heat. conduct barely They problem: own x their ciently generating energy. energy. generating ciently ybys. This stillfrom ananimationshowswhatasingle ow down,” explains Stuart Bale (University (University Bale Stuart ow down,” explains eld, still have to connect to aroom-temper- to connect to have still eld, ies on its own. “It’s quite “It’s quite own. on its ies ©2020 Sky&Telescope. AllRights Reserved. companied byan S-shapetwistinthemagneticfi cross (B), andthensendingaburstofparticles acceleratingoutward ac- magnetic fi eldlinesmeet(A),connectingatthe point where theywould Sun byaprocess. Here, calledinterchangereconnection twoopposing the reorganization ofmagneticfi eldsnearer thevisiblesurfaceof waves ofso-called thousands identifying to crucial been have fl particles ofcharged sea the watch to past. sweeping particles fi electric and magnetic outthe feel to fi and magnetometers three its uses FIELDS Meanwhile, temperature. and direction, speed, density, particles’ Cup, measure to Probe Solar the including ments, instru- three uses SWEAP forces. combine suites instrument star. our around exists that environment unique the scientists fi Parker’s from Data First Encounters p p are fi rstaccelerated,themissionhopestounderstandtheirorigin. the solarwind.Bysamplingcharged particlesclosertowhere they below Parker that’s creating these impulsive things that are are that things impulsive these creating that’s Parker below fl ips in the magnetic fi magnetic the ips in GOING TOTHESOURCE SWITCHING SOURCE Together, these measurements provide the data necessary necessary data the provide measurements Together, these FIELDS and SWEAP Parker’s wind, solar the To study These sudden bursts of speedy particles come with 180° with come particles ofspeedy bursts sudden These crashing over the spacecraft ( spacecraft the over crashing ABC skyandtelescope.org reconnection Interchange rst three perihelia have already shown shown already have perihelia three rst eld. “There’s some dynamics down down dynamics some “There’s eld. One potentialexplanationofswitchbacks is An artist’s conceptshowsParkerfl S&T: elds entrained in the the in entrained elds owing by — and they they —and by owing Apr. 2020, p. 10). eld (C). eld ve voltage sensors sensors ve voltage • N OVEMBER 2020 switchback Escaping ying into ying rogue rogue 8/17/20 10:45 AM 25 ART1_Parker.indd 26 26 Solar Close-up 10 10 detecting intheir respective energy ranges. the barsindicate how manyparticlespersecondthe instrumentswere and high(1million–1.8millioneV) energies. Boththecolorandlengthof of theenergetic particlesare protons, atbothlow(30,000–200,000 eV) the Sun,withfewgapsbetweenOctober 2018andJanuary2019.Most tored particleenergies anddensitiesthroughout thefi rstpassaround S thing happens. reach, Parker’s beyond still corona, the in down deep words, other In explains. Bale wind,” the outby carried being NOVEMBER 2020 p magnetic fi magnetic the When surface. solar the atornear reconnection magnetic Case. says surprising,” is ofthem size the and ofthem number sheer “The time. the all everywhere, ing it’s happen- surface, solar the nearer events these producing whatever’s —basically, thought previously than prevalent more and transient more both were events the that revealed ButParker missions. Ulysses and Helios the by collected data outside. particles the as fast as twice fl are switchback magnetic this within particles The across. itis than longer 50 times about that’s Sun the ating them. ating acceler- to addition in particles heating be would hand, other on the same.” Reconnection, the basically are switchbacks the outside plasma the and switchbacks the inside plasma the like us to itlooks “because says, Bale of reconnection,” Parker. past zooms later, much then, that ofparticles aburst loose lets process —the there to here Higher-energy protonsdetectedpersecond(1million-1.8 eV) -shape twist in the magnetic fi magnetic the in twist -shape Lower-energy protonsdetectedper second(30,000-200,000eV) –2 –4 SPED-UP PARTICLES By the time it reaches Parker, the event appears as a huge ahuge as appears event the Parker, itreaches time the By Some have suggested that the rogue waves come from from come waves rogue the that suggested have Some in switchbacks ofthese signatures seen had Scientists “But my own feeling is that they are not direct evidence evidence direct not are they that is feeling “But myown Perihelion Perihelion eld reorganizes — an open fi open —an reorganizes eld SKY &TELESCOPE •SKY 0.2 a.u. 10 IS –1 IS’s energetic particleinstrumentsmoni- 10 0.4 a.u. –3

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s s 1 a degree or two,” McComas says. says. ortwo,” McComas a degree by butjust Sun, ofthe view outofthe “It’s completely shield. created them can be tricky. tricky. be can them created that processes the to particles the connecting So instruments. previously thought. thought. previously than common more much be may they that it’sand showing IS capture, itcan particles of number the To volts. maximize ofelectron millions to thousands from ofenergies, range awide across particles stantly fl stantly con- —are number in few —though particles now, these as times, quiet during Buteven storms. ofsolar Reveres Paul energy. that times 10 100,000 to from anywhere mph), particles (almost 1million energetic solar km/s at400 streams typically wind solar the While brethren. their than paths different following speed, near-light to ate acceler- somehow corona the in particles ofcharged fraction tiny Some wind. solar is Sun the from comes ofwhat all Not Harbingers of Storms fi then effi can they that so bit, alittle particles accelerate that ones the do?” ofthem rest noneofthe almost and particle million-electron-volt the upbeing ends proton particular some itthat is “Why career: ofhis beginning the since had hehas questions many one ofthe answering start fi can McComas So Earth. near apart tease sible to the [switchbacks] in more of their original state,” Case says. Case state,” original [switchbacks] oftheir more in the see we’ll that is closer ofgetting whole point “The fun. the half is scenarios possible the over Thinking entirely. else something or waves, ol’ Alfvén plain reconnection, magnetic involves mechanism that whether corona, solar the heats what about me.” with disagree would people “Reasonable headds: outthere, idea only the fl they’re that big so be to grown have that waves Alfvén seeing “We’re just strings. guitar plucked many so like wiggling fi magnetic dothe so movearound, particles charged As plasma. magnetized any about ofjust feature of tor of the Integrated Science Investigation of the Sun (IS Sun ofthe Investigation Science Integrated ofthe tor investiga- principal (Princeton), McComas David explains time,” same atthe you’re that measuring [solar plasma wind] the than regions different quite sampling actually “they’re paths, different oftheir Because Sun. the from outward coil fi magnetic the around spiraling individuals, like more are particles charged these does, wind solar the rst time, IS time, rst ipping over on themselves,” Bale speculates. Butit’s not speculates. Bale on themselves,” over ipping Alfvén waves Alfvén From this vantage point, IS point, vantage From this IS When the Sun is active, these particles can serve as the the as serve can particles these active, is Sun the When The answer, he says, has to do with the very fi very the dowith to has hesays, answer, The Whatever switchbacks are, they’re giving us information information us giving they’re are, switchbacks Whatever heralds be could switchbacks the suggests, Bale Instead, Rather than blowing outward in bulk, the way most of most way the bulk, in outward blowing than Rather ݪ IS has two instruments that together detect energetic energetic detect together that instruments two IS has ciently reach much higher energies later on. For the the on. For later energies higher much reach ciently ying out from the Sun. Sun. the outfrom ying ݪ IS can detect these tiny accelerating events, events, accelerating tiny these detect IS can deep in the corona. Alfvén waves are asimple are waves Alfvén corona. the in deep ݪ IS sits right at the edge of the heat heat ofthe edge atthe right IS sits ݪ IS has access to details impos- details to access IS has elds tied to them, them, to tied elds eld lines that that lines eld can carry carry can rst processes, processes, rst nally nally ݪ IS) 8/17/20 10:45 AM

GREGG DINDERMAN / S&T; SOURCE: MCCOMAS ET AL. / NATURE 2019 DECEMBER 12 ART1_Parker.indd 27 SOLAR ENERGETIC PARTICLES: NASA / PRINCETON / JOHNS HOPKINS APL; WISPR IMAGE: NASA / NAVAL RESEARCH LABORATORY / PARKER SOLAR PROBE into gaseous form. Instead, he thinks the particles are erod- are particles the hethinks Instead, form. gaseous into directly species, by species grains, dust sublimating is heat the hedoesn’t think that says, Howard smooth, so is drop-off ing tosatellitesand astronauts oftheincoming spaceweatherthreat. nessed duringits fi rstorbits.The particlescouldprovide advancewarn- charged particlesrushedahead ofonesucheruptionthatParkerwit- solar radii from the Sun’s surface ( Sun’s the surface from radii solar 10 atleast outto extends region adust-free suggests that away in off drops sunlight dust-scattered from emission the directly. them samples and them into fi magnetic ofthe twists scale small- oreven storms solar large-scale as —such structures revealing measurements, for other Parker’s context provide images The corona. the than brighter ofmagnitude orders 13 is 15 to which itself, Sun the from light the blocking acoronagraph, like acts shield heat The dust. and electrons off scattering sunlight capture to spacecraft ofthe edge the over peeks that telescope shoebox-size aroughly imager, only enough sunlight may instead push them away. them push instead may sunlight enough small become particles the when though Sun, the toward in spiral slowly particles these sunlight, with interactions their to Due remain. particles charged electrically micron-scale but nothing until down grinding collide, fragments their and up break Sun the to close too coming asteroids and Comets system’s solar ofthe region densest the through fl is spacecraft The dust. Sun: the from come actually doesn’t that encounters Parker that thing There’s one other Never theDust Settles Where p a coronalmassejection.IS surface oftheSunthatejectsmaterial outintothesolarsystem,termed we get in closer,” says. in get McComas we as events smaller and smaller and smaller we’re seeing that —is yet close that gotten haven’t we even —and far so things exciting most ofthe “One come. to more much are there “PAUL REVERES” Already, WISPR’s PI Howard and colleagues have seen that that seen have colleagues and WISPR’s PIHoward Already, The Wide-fi Researchers are only starting to untangle the data, and and data, the untangle to starting only are Researchers mass ejection mass ejection Coronal Coronal eld Imager for Solar Probe (WISPR) is Parker’s Parker’s (WISPR) is Probe for Solar Imager eld Flare Flare This schematicshowsanexplosion onthevisible IS scientistsdiscovered that energetic eld — before the spacecraft fl spacecraft the —before eld

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