The power levels shown here are estimated from observations made by NOAA/TIROS of high-velocity electrons and positive ions raining down over the auroral oval. Click here to find out more about how these estimates are made. These electrons are responsible for the auroral lights. All of the energy of these particles is eventually deposited into the Earth's upper atmosphere. However, the energy of these particles is only about 10-30% of the total energy flowing into the atmosphere along the auroral oval. The remainder is deposited by up to million-ampere electric currents as they heat the upper atmosphere. During times of high activity, the power deposited can easily exceed the sum of all the electrical power generated in the United States over the same time interval.