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Aurora
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The Aurora
Introduction: An aurora (northern and southern lights, aurorae [pl]) is a natural light that displays within the sky, usually particular to the polar regions. - Aurorae in the northern latitudes is known as the aurora borealis. - Aurorae in the southern latitudes are referred to as aurora australis. Body: A. History 1. The oldest known auroral citing was written in 2600 B.C. in China. Later, in 1570CE, an unknown artist depicted the aurora by drawing burning candles above the clouds. 2. In 1619CE Gallileo gave a name to the phenomenon: “aurora borealis” after Aurora, the Roman goddess of the morning. 3. Henry Cavendish observed the aurora in 1790 and, using triangulation, estimated that the light is produced 1,000km above the Earths surface. i. concluded that auroral light is caused by currents flowing through the upper atmosphere. B. Formation 1. Aurorae result from the reaction between Earth’s atmosphere and particles that are ejected from the Sun. Emissions of photons within the ionosphere (within the thermosphere) form ionized nitrogen (regaining an electron). Oxygen and nitrogen atoms then return to ground state (lower energy forms). These particles are ionized (excited) by the collision of solar wind particles that are funneled and accelerated along Earth’s magnetic field lines. The excitation energy is lost by the emission of light or by collision with another atom or molecule. i. Oxygen emissions form green or brownish-red light. ii...
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