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8/3/2019 Ste Aurora e

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What is the Aurora?!By HayanonTranslated by Y. NodaSupervised by Y. Kamide

NGDCGDCNGDCGDC


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Auroral breakup seen from directly underneath.

A Message from Galileo Galilei (1564-1642

Hi, I am an Italian scientist raised in Pisa during the lateRenaissance period. Galileo was my first name. At that timein Italy, "famous" people were called by their first namesinstead of their family names. People say I laid thefoundations of modern science.

Following advice from my father, who was a music andmathematics teacher, I enrolled in a medical course at theUniversity of Pisa. I became, however, totally absorbed inmathematics, instead of medical science. Do you know thatthe "Isochronism of the Pendulum" principle, which you learnat high school, is one of my findings? Finally I quit theuniversity.

While working as a private teacher to rear my younger brothers and sisters, I keptdoing research. At the age of 25, my first paper was published and was well accepted,and I was invited to be a Lecturer at the University of Pisa. My father died 2 yearslater.

Twenty years before I was born, Copernicus published the Copernican theory thatour Earth, not the stars in the sky, is moving. But, people hardly believed this theorybecause what we see in daily life is that the sun rises from the eastern horizon andgoes down in the west.

Among other findings of mine are Jupiter's four satellites, craters on the moon'ssurface, and waxing and waning of the moon, all from observations with a Galileantelescope. These discoveries cast questions on the astronomyof that time, as proof of the heliocentric theory. My discoveryof the sunspots was criticized by the advocates who said "whata shame to insist that there are spots on the perfect sun!" Ihad to face the Inquisition several times. When Newton, who

was born in the year of my death, established the dynamics bycombining my findings, I felt my efforts were rewarded.Because of long-time observations of the sun with the naked

eye, my retinas were damaged, and I became blind. My laterpapers were written by dictation.

To the mysterious glow in the sky I gave the name "aurora"after the Roman goddess of dawn. In 1621, a fabulous aurorashowed up in Venice. Even though I had seen auroras severaltimes, that was the one I could never forget. I did not have theslightest idea that the origin of auroras is with the sunspotsthat I found myself! It was not until 200 years later that

people became to know the true scenario for the generation ofauroras.

Leaning Tower of Pisa


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We are almostthere, Mirubo!

if only we canencounter anaurora!!

Oh, we have beenhaving a hard timeall the way.

Where is today's scientificadventure for Mol and herrobotic dog Mirubo?

YellowknifeellowknifeYellowknife

Mol

They are flying overYellowknife, Canada, at62north latitude.

Mirubo

But, finallyit will be

rewarded,

Huffing,puffing...

W h oosh!o sh ! Bo i n g!


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We havefinallyarrived!

Brrr, it'scold!

I am sure wecan expect aspectacular aurorain such coldweather.

Right!

Not right!The temperature hasnothing to do with the

generation of auroras.

Why?! Ah, it's you,Aurora sensei!

What bringsyou here,sensei?

To study theaurora, of course.Now, are you

interested in ...

how auroras arecreated? Yes!!Could youexplain ...

You learned that theEarth is a huge magnetand has the geomagneticfield, didn't you?

The Earth's geomagneticfield is distorted by thesolar wind into a

shape like this.

And, charged particles

are accumulated here.We did.

Yellowknife


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The aurora appears inthe night sky, namely,this part of geomagneticfield lines.

Its shape islike a belt. You are

correct.

That's why we callthis area theauroral belt.

You see from this mapthat the auroral belt issurrounding the geomagneticpole.

The reason why the auroral belt

lies in the arctic is not because itis cold there, but just becausethe geomagnetic north pole happens

The auroral belt will

move toward lowerlatitudes from the polarregions, and will ...

Wow, will aurorasbe seen in Japan?!

Yes, althoughit will be in thefar distant future.

to be presentlylocated at thenorthwest cornerof Greenland.

reach Japan in1000 years.

Wow

!

Cinch,cinch


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We can't waitthat long. Let'swait for anaurora here.

The aurora doesnot show up beforenightfall. Really?

An intense auroraoccurs only on thenight side for some

reason.

I think it'sabout time.

I amfreeeezing!!It's almost30C!!

We have beenwaiting for anaurora for morethan 2 hours.

This is my limit.I can't be here

any longer.

Gasp!!

At night...

But, it's toocold.Huuurry up,

please.

I didn'tknow that.

The auroradoes not occur

at any time?

?????


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Au Au ...

Aurora!!

Aurora,my aurora!!

Fantastic,splendid,super!

Woohoo,yeehaw!

She sometimes

does toomuch ...

Yes!Yes!

Yes!Yes!

Fump!ump!

Yes!Yes!


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That was awonderfulaurora.

Hi, Aurorasensei.

You guysare verylucky!

The aurora isinscrutable.

In the firstplace, theaurora is

caused

by ...

a collection of hot, charged

particles, called a plasma,coming out of the sun.When these charged particlescollide with the Earth'satmosphere, the aurora is

created.

This is called the"auroral breakup."An active one likethis is rare.

It's muchbrighter thanI expected.

I wonder how the

auroral lights aregenerated.


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The aurora hascolors of

blue, and ...

sometimes red inits upper part ofauroral curtains.

Those colors depend on whichchemicals the charged particlescollide with. Green light resultsfrom the collision with the oxygenatoms, and blue from the

nitrogen molecules.

Above 250 km where theatmosphere is thin, theoxygen atoms produce redlight.

It's sobeautiful!

I want to geta closer lookat the aurora.

Let's go up,Mirubo!

We canreach it soon.

A great

idea!

Join us,sensei!!

No, thank you.I will wait for

you here.

Me?

Red

whitish green thatis most common, ...

Green

Blue

Vaa

Smirk

roooooom m


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We willreach it soon.

Now it's veryclose to us ...

I hope ...

Noooop!

We are notapproachingthe auroraat all!!

I have alreadyreached mylimit.

Mirubo, no matterhow hard you try,

you will never catchthe aurora.

Welcome back!

What?!

The aurora seems to be

just above the clouds.In fact, it is very high.Look at this picture.

You need to ride theSpace Shuttle to fly ashigh as the aurora.

Airplane Mt. Everest

Ozone Layer

10 min.later

Space Shuttle

Gasp

Pant

Pant,pant...

Heh,heh


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Why didn't youtell me?

You think Itricked you oram unkind?

The aurora lookscloser than it really

is.

When you see anaurora from an

airplane ...

you may feel that theairplane will flyinto the aurora.

Because the Earth isround, one thinks that

Yes.

the aurora in thefar distance isat the same levelas an airplane.

The aurora isactually located atabout 10 timeshigher than wherean airplane flies.

Now Iunderstandwhy I was

not successfulin reaching the

aurora.SighSigh

...

...


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Auroras have attimes been observedin Japan.

Really?!

Yes, but they onlysaw the upper part

Because of its redlight, people often ... have mistaken it for

a forest fire.

That doesn'tlook like curtainsfrom this

distance?!

of the auroral

curtains from adistance.

I see.


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I will never gettired of watchingaurora.

No wordscan expresshow wonderfulit is.

I have been

watchingauroras for

dozens of years.

But now I amfreezing.Why don't wego inside.

A lot of questions stillremain unsolved.Besides, there are notwo identical auroras.

I want to keep onwatching aurora aslong as possible.


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What is the Aurorahat is the Aurora?!!Nice to meet you again, Sensei!

I saw a live TV program about auroras. Thatwas amazing.

Yes. The aurora is a magnificentphenomenon, presenting a lot of unsolvedmysteries. Hope you won't be too hard onme.

First, why does the aurora move justlike a curtain does, stretching out in the vastsky?

Nobody would notice even if I could cuta little piece out of the aurora curtain.

You could nicely decorate your roomwith it, Mirubo. The auroral curtain ischaracterized by its folds, showing thedirection of geomagnetic field lines. Chargedparticles coming down from space areaccelerated along the magnetic field lines,then collide with the upper atmosphere. Thiscollision creates the aurora.

Hum. The folds of the auroral curtainbecome inclined more at lower latitudes.The lower the latitude, the more the auroral

curtain's folds become inclined.Correct. The magnetic field lines are

horizontal at the equator. Thus, auroras seenthere must look like a UFO.

Do auroras occur in the equatorialregions??

In India experiments to create anartificial aurora were conducted. Peoplethere were so surprised to see the light, andlocal police offices received constant phone

calls, claiming that a UFO had arrived.

Sensei, if I count the folds of auroralcurtain one by one, will I find the number ofthe magnetic field lines?

No, because the magnetic field linesare invisible and not countable.

Why? We can see the folds up there.

Pardon me, I do not have an answer.

Well, then, why does the aurora movelike it's dancing?

The aurora does not move, Mol.

Oh, I do not quite follow you.

Take an electric bulletin board or neonsigns for example. Although light bulbs onthe board never move, letters displayedthere seem to shift one after another. Tomake certain letters formed and displayed,designated light bulbs should be lightened.The aurora "moves" in the similar way.Signals traveling from space down to theEarth decide which part of the sky glows.

It sounds like space is drawing apicture in our sky.

Exactly. The aurora works in a mannersimilar to that of your TV at home. In otherwords, the solar-terrestrial space displaysthe aurora on the huge screen above us, justthe way producers make TV programs.Scientists are working on trying tounderstand the nature of space by observingthe aurora.

Isn't it interesting that the aurora is aTV program produced by space for thenatural screen of the sky, and we see it onTV?!

I understand that the aurora'sbirthplace is the sun. Why then does it occuronly in the nightside of the Earth? Does italso exist in the dayside, but just cannot beseen?

The aurora is active on the night side.No matter how bright the sky is, we cancapture the dayside aurora with radars.Charged particles coming from the sun travelinto the nightside of the Earth.

How do they travel? And, why does theaurora often suddenly brighten up or startmoving?

Sorry, but those questions cannot beanswered to my knowledge.

Don't mind, sensei. Are you able toforecast the aurora?

Yes, we can for some types of auroras.A large-scale aurora can be forecasted fromsatellite observations and geomagnetic field

observations. Take a look! An aurora willappear in northern Canada in about an hour.

Whoopee! Let's go Mirubo!


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A photograph from the Space Shuttle Discovery above auroral displays. Courtesy of NASA

Aurora reflected on a lake, justbefore dawn. Photo by YuichiTakasaka

Needle-leaved trees and aurorashooting up the sky. hoto byNorihisa Sakamoto


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Auroras were seen in Japan several times in lateOctober to early November, 2003. These photoswere taken in Rikubetsu, Hokkaido, showing red

illuminations near the northern horizon. Photos byRikubetsu Astronomical Observatory

NGDCGDC

Solar-Terrestrial Environment Laboratory (STEL),Nagoya University

STEL is operated under an inter-university cooperative systemin Japan. Its purpose is to promote "research on the structure

and dynamics of the solar-terrestrial system," in collaboration with a number ofuniversities and institutions both in Japan and abroad. The Laboratoryconsists of four research Divisions: Atmospheric Environment, Ionosphericand Magnetospheric Environment, Heliospheric Environment, and IntegratedStudies. The Center for Joint Observations and Data Processing is alsoaffiliated to the Laboratory to coordinate joint research projects and constructdata bases. At its seven Observatories/Stations, ground-based observationsof various physical and chemical entities are conducted nationwide.http://www.stelab.nagoya-u.ac.jp/

National Geophysical Data Center (NGDC)Space Environment Center (SEC)National Oceanic and Atmospheric

Administration (NOAA)

NGDC and SEC of NOAA, located in Boulder, Colorado, are part of the USDepartment of Commerce. NGDC provides scientific stewardship, productsand services for geophysical data describing the solid earth, marine, andsolar-terrestrial environment, as well as earth observations from space.Continually monitoring Earth's space environment, SEC provides reliable anduseful solar-terrestrial information, conducts research and development

programs to understand the environment, and plays a leadership role in thespace weather community.http://www.ngdc.noaa.gov/ http://www.sec.noaa.gov/

HayanonGraduated from the Department of Physics of RyukyuUniversity, Hayanon, a writer and cartoonist, hascontributed a number of serials in popular magazines onthe basis of her strong background in science andcomputer games. Her consistent writing style,expressing a love for science, is well accepted.

http://www.hayanon.jp/

Kodomo no Kagaku (Science forChildren)

Kodomo no Kagaku, published by the SeibundoShinkosha Publishing Co., Ltd. is a monthly magazine for

juniors. Since the inaugural issue in 1924, the magazinehas continuously promoted science education byproviding various facets of science, from scientificphenomena in everyday life to cutting edge researchtopics. http://www.seibundo-net.co.jp/

"What is the Aurora?!" is published with cooperation of Kodomo no Kagaku, and with advice by K.

Shiokawa. Mol, Mirubo, and Sensei thank E. Kihn, Terry Onsager, Bernie Shizgal, and Roland Tsunodafor their help in preparing the English version of our story.

April 2004 All rights reserved.

Produced by the Solar-Terrestrial Environment Laboratory, Nagoya Universityunder the auspices ofthe Ministry of Education, Culture, Sports, Science and Technology.

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