Designed to scan the heavens thousands to billions of light-years beyond the solar system, the Fermi Gamma-ray Space Telescope has now recorded some more down-to-Earth signals. During its first 14 months of operation, the flying observatory has detected 17 gamma-ray flashes associated with terrestrial lightning storms.
During two recent lightning storms, Fermi recorded gamma-ray emissions of a particular energy that could only have been produced by the decay of energetic positrons, the antimatter equivalent of electrons. The observations are the first of their kind for lightning storms. Michael Briggs of the University of Alabama in Huntsville announced the puzzling findings Nov. 5 at the 2009 Fermi Symposium.
It’s a surprise to have found the signature of positrons during a lightning storm, Briggs said.
During lightning storms previously observed by spacecraft, energetic electrons moving toward the craft slowed down and produced gamma rays. The unusual positron signature seen by Fermi suggests that the normal orientation for an electric field associated with a lightning storm somehow reversed, Briggs said. Modelers are now working to figure out how the field reversal could have occurred. But for now, he said, the answer is up in the air.
I don’t think that was a deliberate pun. It’s also interesting as all get-out.
So much science to learn – and we are surrounded by nutballs still trying to count angels on pinheads.