1. Auroras occur when energized electrons from the sun penetrate Earth's atmosphere. The electrons excite gas particles -- mostly nitrogen and oxygen -- in the atmosphere, which then emit light. Different types of gas particles emit different wavelengths (and therefore different colors) of light. Oxygen emits in deep yellow and deep red, and is more prevalent at lower altitudes, nitrogen emits in blue and purplish red, and comes from higher altitudes.
2. The energy from the sun is mechanical energy and is stored as electromagnetic energy, but neither glows like auroras. The auroras are produced closer to the upper atmosphere by energetic particles, energized by the Sun's energy that was stored in Earth's environment. The ribbon shape of the auroras is caused by the bar-magnet shape of Earth's magnetic field that lines the particles along sheets, like onion layers, around the planet. Those onion layers meet at the north and south pole and intersect the Earth's atmosphere, and that is where the particles deposit their energy. The onion layers, as they cross the Earth's atmosphere define a line, or sheet, and give the aurora its sheet-like appearance.
3. Yes, in fact the auroras are not centered around the North geographic pole, but around the North magnetic pole, which is now 600 miles away towards the Eastern American continent sector.
4. Yes, the Van Allen belts are a key part of the storm process. The belts are rings of charged particles that surround earth and are held in place by the earth's magnetic field. They get filled with freshly energized particles during a storm and on occasion new belts appear and last for days, months or years. The Van Allen belts are very dynamic during a storm and understanding their storm-time behavior is a major goal in space research today.
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