Red Sprites and Blue Jets
June 14, 2002
This June is the 250th anniversary of Benjamin Franklin's famous experiment with lightning (the exact date of the experiment isn't known). To demonstrate that lightning indeed had an electric field, he used a kite and a key to attract a lightning bolt. This rather dangerous experiment proved his point and resulted in his invention of the lightning rod.
In the last decade, a new form of lightning has been identified that seems to be generated between Earth and space - high above thunderstorms. Red sprites and blue jets are the signatures of this "space lightning." The photo above was taken by an astronaut on board the space shuttle and shows what has become known as a red sprite. Red sprites are flashes of red light that last just a few thousandths of a second. These curious flashes can reach as high as the lower edge of the thermosphere, about 90 km high, and may spread over extensive areas of the sky. Blue jets, on the other hand, appear to emanate directly from the tops of thunderstorm clouds and zip through the stratosphere at speeds of approximately 100 km a second.