aurora under mod

8/3/2019 Aurora Under Mod

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THE AURORA

By,

Fg Offr K.S.SUDHARSHANAN16 INDRA (0)


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CONTENTS

INTRODUCTION

CHARACTERISTICS

THE PHENOMENON

HISTORICAL OVERVIEW

SPACE PROGRAMS

TYPES

AURORA AS ATOMIC PHYSICS

EFFECTS OF AURORA IN OTHER PLANETS

CONCLUSION


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INTRODUCTION

AN AURORA - A NATURAL LIGHT DISPLAYIN THE HIGH LATITUDE REGIONS.

SEEN NEAR THE MAGNETIC POLES.

ILLUMINATE THE HORIZON AS GREENISH

GLOW OR A FAINT RED- SUN RISE FROMAN UNUSUAL DIRECTION.


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CHARACTERISTICS

oAppear in a narrow belt around both the northern andsouthern magnetic poles.

oHas a variety ofshapes, colors, and structures

oContinuously changing in time.


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PLACES OF OCCURANCE

Most aurora occur in a band known as the

auroral zone Typically 3 to 6 in latitudinal extent.

The auroral zone is 10 to 20 from themagnetic pole.

During a heavy solar storm , the auroral zonewill expand to lower latitudes.

Aurora australis (11 September 2005) as

captured by NASA's IMAGE satellite,
http://en.wikipedia.org/wiki/File:Aurora_australis_20050911.jpg


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AURORA BOREALIS

In northern latitudes -AURORA BOREALIS(or the

northern lights)

AURORA -Roman goddess of dawn,

BOREAS -the Greek name for the north wind.

Viewed at Canada, arctic circle, Scandinavian islands,

Alaska.


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AURORA AUSTRALIS

Southern counterpart, theAURORA AUSTRALIS (or

the southern lights),

Identical features to the aurora borealis

Changes simultaneously with changes in northern

auroral zone

Visible from high southern latitudes in Antarctica,

South America and Australia.


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THE PHENOMENON

Display starts with a phosphorescent glow over the

horizon and arch is lit.

Arch drifts up over in the sky as new arches are lit and

follow the first one.

Small waves and curls move along the arches.

Rays of light shoot down from space which spread allover the sky.


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THE PHENOMENON

After 10 to 20 minutes the activity decreases, bands

spread out, disintegrating in a diffuse light all over the

sky.

Take a look

Magnificent overhead aurora.
http://var/www/apps/conversion/current/tmp/scratch1396/Aurora%20-%20YouTube.flvhttp://var/www/apps/conversion/current/tmp/scratch1396/Aurora%20-%20YouTube.flv


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HISTORICAL OVERVIEW

The Inuit people in Northeast Canada believed :

"The sky is a huge dome of hard material arched over the

flat earth and outside of it there is light. In the dome there

are a large number of small holes and through these holesyou can see the light from the outside when it is dark."

The Eskimos believed aurora was the dance ofanimal

spirits (deer, seals and salmon).

Aristotle and Hesiod , ancient Greek poet(8th century

B.C.) mentioned aurora in their writings


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IN THE MIDDLE AGES

In central Europe the Northern Lights were

considered a bad omen.

Warned of illness, plague and death. Whenred, they signaled the outbreak ofwar.


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IN MORE RECENT TIMES

1619 - Galileo christened the Northern Lights as :

Aurora Borealis- Northern Dawn.

The existence of Southern Lights (Aurora

Australis) was still unknown in Europe.

colored woodcut showing an aurora at Nuremberg on October 5, 1591.


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IN MORE RECENT TIMES

The Aurora Australis was first sighted byEuropeans in the end of the 18th century,during the expeditions ofCaptain James

Cookaround Australia.

During November 2003 storm, red aurora reached as far south as

Athens, Greece.


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THEORIES

1716- Edmund Halley considered particles thatmove along the field lines of the earths

magnetic field as the origin.

1733- French scientist de Mairan proposed

interaction of light material with the terrestrial

atmosphere.

- also connection with sunspots.


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THEORIES

1895 - Scientist KristianBirkeland conducted

TERELLA experiment.

Discovered energetic electrons ejected from sunspots,

then directed to the Earth.

They are guided to the Earth's polar regions by themagnetic field, produce the visible aurora.
http://en.wikipedia.org/wiki/File:Birkeland-terrella.jpg


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THEORIES

1957-1958- International geophysical year, Yasha

Feldsteinproposed the concept of the AURORALOVAL.

The locus of usual appearance of auroras .

Each oval is up to 3,500 km in diameter and a few

hundred km thick.


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AURORAL OVALS


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THE SPACE AGE

Advancement in science and technology allowed

scientists to observe and record aurora from third

dimension

Imaging the aurora from above by satellites permitted

simultaneous observations of large areas of aurora andspectacular views.

View of aurora from International space station
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpg


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SPACE PROGRAMS

Defence Meteorological Satellite Program (DMSP),

USA 1962

Canadian ISIS-2 spacecraft in 1972.

Dynamics Explorer (NASA)- 1981

STS-39 - 1991

Hubble space telescope

SPACE PROGRAMS
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpg


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SPACE PROGRAMS

International Space Station (ISS)- 1997

IMAGE(Imager for Magnetopause-to-Aurora GlobalExploration), NASA - 2000

THEMIS(Time History of Events and Macro scale

Interactions during Sub storms),NASA mission - February

17, 2007


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TYPES

Aurora is classified as DIFFUSE AURORA - a featureless glow in the

sky which may not be visible to the naked eye .

defines the extent of the auroral zone.

DISCRETE AURORA - sharply defined features.

vary in brightness from just barely visible

to the naked eye to bright enough to read a newspaper

at night
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpg


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THE AURORA AS ATOMIC PHYSICS

Physicists say - the aurora is a large-scale electrical

discharge phenomenon in the high-altitude

atmosphere.

Results from quantum leaps in oxygen and nitrogenatoms.

Energetic electrons streaming along geomagnetic

field lines hit and excite atoms and molecules.


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THE AURORA AS ATOMIC PHYSICS

Above a hundred kilometers, oxygen and nitrogen

atoms are energized by energetic particles.

The auroral light results from the de-excitation of

these particles.

The color, shape, and intensity depend on the energy

of the electrons.

Oxygen emissions -Green or brownish-red.

Nitrogen emissions - Blue or red.
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpg


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EFFECTS OF AURORA

THE LARGE SCALE ELECTRICAL DISCHARGEHAS SEVERE EFFECTS ON:

AIRCRAFT MOVEMENT

SATELLITE COMMUNICATION

POWER LINES

GPS
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpg


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AURORA IN OTHER PLANETS

Jupiter and Saturn - magnetic fieldsmuch stronger than Earth

Jupiter's field strength - 4.3 gauss,

0.3 gauss for Earth.

Uranus and Neptune have also been

observed to have auroras.
http://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Aurora_Borealis.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpg


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CONCLUSION

Auroras are natural phenomenon of magnificent

display of light , visible only at polar regions.

Many natural phenomenon goes unnoticed, we shouldmake time to know about our earth.
http://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Red_and_green_aurora.jpghttp://en.wikipedia.org/wiki/File:Aurora_Australis_From_ISS.JPG


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http://en.wikipedia.org/wiki/File:Aurora_Australis_From_ISS.JPG

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