The Dancing Lights
Auroras have been emitting in our, and other planets’ skies as long as the Solar System has been in motion. In 1619 A.D., Galileo Galilei coined the term "aurora borealis" after Aurora, the Roman goddess of morning. He had the misconception that the auroras he saw were due to sunlight reflecting from the atmosphere. (Angelopoulos, 2008). In 1741, Hiorter and Celsius noted that the polar aurora is accompanied by a disturbance of the magnetic needle. In 1820, Hans Christian Oersted discovered electromagnetism. André-Marie Ampére deduced that magnetism is basically the force between electric currents. In 1851, Samuel Schwabe, a German amateur astronomer, announced the discovery of the 11-year sunspot cycle, and in 1859, Richard Carrington in England observed a violent and rapid eruption near a sunspot; 17 hours later a large magnetic storm began. In 1900-3, Kristian Birkeland experiments with beams of electrons aimed at a magnetized sphere ("terrella") in a vacuum chamber. The electrons hit near the magnetic poles, leading him to propose that the polar aurora is created by electron beams from the Sun. Birkeland also observes magnetic disturbances associated with the aurora, suggesting to him that localized "polar magnetic storms" exist in the auroral zone. In 1958, Eugene Parker (Chicago) proposes the theory of the solar wind. 1981, High resolution images are obtained by Lou Frank's group in Iowa of the entire auroral zone, using the Dynamics Explorer satellite. (Stern & Peredo, 2005) This is the major timeline of how auroras came to be discovered and understood.
Now that the history is covered, I can get down to the nitty gritty of how they are able to appear in the sky. Auroras are caused by the collision of energetically charged particles with atoms in the high altitude atmosphere (Thermosphere). These charged particles come from the Magnetosphere, solar winds, and Earth, which are then directed by Earth’s magnetic field into the atmosphere. These charged particles come in from those areas, and atoms in the Thermosphere collide and the explosion of their collisions are auroras. (Feldstein, 1963)
These auroras often occur in the Auroral Zone, which expands during a geomagnetic storm. There are two types of auroras, diffuse and discrete. Diffuse auroras are featureless glows in the sky that may not be visible to the naked eye,...