Nature News: The High Frequency Active Auroral Research Program ( HAARP), near Gakona, Alaska, has for 20 years used radio waves to probe Earth's magnetic field and ionosphere. One of the most visible results of the experiments—since the facility upgraded its transmission power output from 1 to 3.6 megawatts—is that they can create lights in the sky that are similar to auroras.The technique works by using the high-frequency radio waves to accelerate electrons in the atmosphere, increasing the energy of their collisions and thereby creating a glow.In February last year, HAARP unexpectedly managed to induce a strange bull's-eye pattern in the night sky. "This is the really exciting part—we've made a little artificial piece of ionosphere," said US Air Force Research Laboratory physicist Todd Pedersen to Nature's Naomi Lubick.
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HAARP creates bull's-eye in the sky
13 October 2009
© 2009 American Institute of Physics