1. Auroras
Paintings in the Sky
Lokhaze Ali

2. Aurora
• Meaning of Aurora is Dawn, Daybreak or
Sunrise
• Aurora was the Roman Goddess of
Sunrise

3. Roman Goddess Aurora
Aurora (painting the dawn)
Just before the sun rises there is
a hush all over the land in
anticipation of the arrival of
Aurora the Goddess of dawn.
Using her rainbow coloured
palette she paints the sky and
clouds with the dramatic colours
and light of the imminent dawn,
until with a burst of brightness
the sun emerges and another day
begins. Her work is never done as
she travels the world painting a
million dawns in a continuous cycle.
With each dawn comes a new day
to celebrate and enjoy.

4. Creation of Auroras
• Auroras are caused by the
bombardment of solar electrons
on oxygen and nitrogen atoms. The
electrons literally excite the oxygen and
nitrogen atoms high in the atmosphere
to create the beautiful light show we
know as an aurora.

5. What causes an Aurora?

6. Auroras
• http://www.nasa.gov/multimedia/videogaller
y/index.html?media_id=97423582

7. Polarization
• Polarization is a property of certain types
of waves that describes the orientation of
their oscillations. Electromagnetic waves,
such as light and gravitational waves
exhibit polarization.
• By convention, the polarization of light is
described by specifying the orientation of
the wave's electric field at a point in space
over one period of the oscillation.

8. Linear polarization
The two orthogonal (perpendicular)
components are in phase. In this case
the ratio of the strengths of the two
components is constant, so the
direction of the electric vector (the
vector sum of these two components)
is constant. Since the tip of the
vector traces out a single line in the
plane, this special case is called linear
polarization.

9. Circular Polarization
The two orthogonal components have
exactly the same amplitude and are
exactly ninety degrees out of phase. In
this case one component is zero when
the other component is at maximum or
minimum amplitude. There are two
possible phase relationships that satisfy
this requirement: the x component can
be ninety degrees ahead of
the y component or it can be ninety
degrees behind the y component. In this
special case the electric vector traces
out a circle in the plane, so this special
case is called circular polarization.

10. Elliptical Polarization
• Another case is when the two
components are not in phase and
either do not have the same
amplitude or are not ninety
degrees out of phase, though
their phase offset and their
amplitude ratio are
constant. This kind of
polarization is called elliptical
polarization because the electric
vector traces out an ellipse in
the plane (the polarization
ellipse).

11. Polarized Effect
A polarizer filters out the polarized component of light
from the sky in a color photograph, increasing contrast
with the clouds (right).

12. Auroras
• http://vimeo.com/35618405