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aurora's underfoot

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presented by science at nasa

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glowing green and red shimmering

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hypnotically across the night sky the

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aurora borealis is a wonder to behold

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long time sky watchers say it is the

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greatest show on earth

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it might be the greatest show in earth

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orbit too

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some 400 kilometers above our planet

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astronauts on board the international

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space station enjoy a unique view of

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earth's polar lights up close and

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personal

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we can actually fly into the auroras

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says astronaut don pettit a flight

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engineer for iss expedition 30.

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it's like being shrunk down and put

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inside of a neon sign

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auroras are caused by solar activity

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gusts of solar wind and coronal mass

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ejections strike earth's magnetic field

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rattling our planet's protective shell

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of magnetism

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this causes charged particles to rain

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down over the poles lighting up the

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atmosphere where they hit

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the physics is akin to what happens in

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the picture tube of a color tv

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incoming particles are guided by earth's

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magnetic field to a pair of donut-shaped

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regions called auroral ovals

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there's one around the north pole and

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one around the south

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sometimes when solar activity is high

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the ovals expand and the space station

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orbits right through them

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that's exactly what happened in late

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january 2012 when a sequence of powerful

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solar flares sparked a light show that

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pettit says he won't soon forget

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the auroras could be seen as brightly as

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city lights on the earth below and even

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in the day night terminator of the

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rising and setting sun

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it was simply amazing

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pettit is a skilled astrophotographer he

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and other members of the crew video

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recorded the displays producing footage

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that officials say is some of the best

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ever taken from earth orbit

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the videos capture the full range of

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aurora colors red

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green and many shades of purple

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these hues correspond to different

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quantum transitions in excited atoms of

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oxygen and nitrogen

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the precise color at any altitude

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depends on the temperature and density

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of the local atmosphere

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red auroras reach all the way up to our

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altitude 400 kilometers above earth says

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pettit

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sometimes you feel like you can reach

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out and touch them

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green emissions on the other hand tend

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to stay below the space station he says

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they move like a living shag carpet of

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lights we fly right over them

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surprisingly pettit does not find this

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unsettling

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it is not disorienting to see auroras

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underfoot he says

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perhaps it is because i have been up

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here so long

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what he does find disorienting is the

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meteors occasionally we see a meteor

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burning up in the atmosphere below and

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this does look strange

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you should be looking up for meteors not

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down

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as marvelous as these sites are pettit

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has seen better

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he was the science officer for iss

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expedition 6 back in 2003 when the

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auroras were even stronger than they

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were now

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but this expedition is not over yet he

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points out hopefully

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indeed more auroras are in the offing

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following some recent years of deep

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quiet the sun is waking up again

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solar activity is now trending upward

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with a maximum expected in early 2013.

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this means the greatest show on earth

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and in earth orbit is about to get even

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better

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for updates and more great video from