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  1. 1. AurorasPaintings in the Sky Lokhaze Ali
  2. 2. Aurora• Meaning of Aurora is Dawn, Daybreak or Sunrise• Aurora was the Roman Goddess of Sunrise
  3. 3. Roman Goddess AuroraAurora (painting the dawn)Just before the sun rises there isa hush all over the land inanticipation of the arrival ofAurora the Goddess of dawn.Using her rainbow colouredpalette she paints the sky andclouds with the dramatic coloursand light of the imminent dawn,until with a burst of brightnessthe sun emerges and another daybegins. Her work is never done asshe travels the world painting amillion dawns in a continuous cycle.With each dawn comes a new dayto celebrate and enjoy.
  4. 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. 5. What causes an Aurora?
  6. 6. Auroras• y/index.html?media_id=97423582
  7. 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 waves electric field at a point in space over one period of the oscillation.
  8. 8. Linear polarizationThe two orthogonal (perpendicular)components are in phase. In this casethe ratio of the strengths of the twocomponents is constant, so thedirection of the electric vector (thevector sum of these two components)is constant. Since the tip of thevector traces out a single line in theplane, this special case is called linearpolarization.
  9. 9. Circular PolarizationThe two orthogonal components haveexactly the same amplitude and areexactly ninety degrees out of phase. Inthis case one component is zero whenthe other component is at maximum orminimum amplitude. There are twopossible phase relationships that satisfythis requirement: the x component canbe ninety degrees ahead ofthe y component or it can be ninetydegrees behind the y component. In thisspecial case the electric vector tracesout a circle in the plane, so this specialcase is called circular polarization.
  10. 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. 11. Polarized EffectA polarizer filters out the polarized component of lightfrom the sky in a color photograph, increasing contrastwith the clouds (right).
  12. 12. Auroras•