Sound Effect Sound Effect Sound Effect Narrator: At any given moment about 1,800 thunderstorms are in progress somewhere on the globe. New observations by NASA's Fermi Gamma-ray Space Telescope show that thunderstorms make antimatter. The process starts with a terrestrial gamma-ray flash, or TGF; an intense pulse of gamma rays originating from thunderstorms. These dots mark TGF's observed by Fermi's Gamma-ray Burst Monitor during the spacecraft's first eight months of operations. Researchers estimate that there may be as many as five hundred TGF's each day. On December 14, 2009, as Fermi passed over Egypt, it spotted a TGF produced by a thunderstorm in Zambia The TGF was over the spacecraft's horizon where Fermi couldn't see it. So how could FermiI have detected it? Scientists believe that the TGF process begins with thunderstorm's intense electrical field. Electrons within this field become accelerated upward above the storm where the air is thin, the electrons can ramp up to speeds nearly as fast as the speed of light. When these ultra-fast electrons encounter an atom, they emit gamma rays. Very rarely, one of these gamma-ray photons grazes an atom and transforms into a pair of particles. One, an electron, is normal matter; the other is antimatter, the electron's opposite, called a positron. The gamma rays travel in straight lines, but the charged particles spiral along lines of Earth's magnetic field. And that was the route to Fermi. The particles created by the TGF rode upwards on magentic field lines and then struck the spacecraft. The positrons annihilated when they struck electrons in Fermi creating a flash of gamma rays. For an instant Fermi became a gamma-ray source and set off its own detectors. A fraction of a second later, some of the particles were bounced back along the same magnetic field line. They again passed through Fermi and again produced gamma rays. The spacecraft has observed this phenomenon in at least four other occasion. So the next time lightning flashes and thunder roars remember-you may be witnessing antimatter in the making. Music Sound Effect Sound Effect