}Name: "Aurora Borealis" Latin for "Northern Dawn"
}One
of the most impressive natural phenomena
}First
recorded incident: “La Caverne de
Lascaux” SW France
}Fascinates
and terrifies humans
}Aurora
Legends: Every northern culture has oral legends about the aurora, passed down
for generations
Medieval Age
People believed that the polar light is a
bad omen.
Fearing the red light.
Especially
while it is very rare in
Middle Europe.
The aurora was for example described as
heaven
battles or as candles
•This Norwegian polar explorer tried to reach the north pole with
his ship Fram in 1895-96
•He was blocked by ice but made many woodcuts and drawings about the
aurora
Northern Light Times
Solar phenomenon in
the Ionosphere.
Occurs while periods
of high solar activity.
80-200km above
ground connected to the
magnetosphere
Solar Winds
}Solar winds are caused by
energy released by the sun
}Extension of Sun’s corona
}High speed plasma
A long way towards earth
}Interactions with the
Ionosphere – solar wind (speed 450km/h) carries a weak magnetic field
}Interaction between this
and the magnetic field of earth
}Changes form of the earth‘s
magnetosphere
}energy dissipates into
gaseous form, causing Aurora’s or stays in electric form
}Dangers: Interrupting
satellite transmissions / power grids
Morphing the magnetic field
Earth has a magnetosphere surrounding the planet. Solar wind flowing
past the earth. Solar wind and the magnetosphere are two electrically
conducting fluids with magnetic fields. Plasma and atoms collide. Energy
flow causes a change in magnetic field
Magnetosphere
}Earth
has a dipole magnetic field similar to a bar magnet
}Invisible
magnetic field lines entering at the north pole, exiting at the south pole
}periods
of high solar activity interaction between the solar wind and magnetosphere
}solar
winds effect the comet shape
Forming of Auroras
}Repeat:
solar wind collides with atoms of the upper atmosphere
}Altitudes
of 80-200km
}Frequency
usually follows the 11-year sunspot maximum cycle.
}Peak
3 years after the peak of the sunspot cycle.
The Aurora Oval
1.The aurora is often visible
at high latitudes
2.Magnetic field pressure is
strongest
3.Most often: Oval located
between 65 and 75 degrees latitude
4.Oval ranges from 500 to
1500 km in width
5.Zone statistically defined
A
aurora seen from space
Where the aurora can be seen
}Number
of nights per year aurora
can be seen at certain locations
}Northern
Norway:
100 nights each per year
}Rest
of Norway:
10 nights every year
}Middle
Europe:
1 to 0,1 nights each years
Complex formations out of the shown elements:
}Curl
}Curtain
}Omega band
}Corona
}Pulsating aurora
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