>“We didn’t expect there to be so much iron density at that altitude. It comes from meteors that enter the atmosphere at high speed, burn up and [then] the meta

>“We didn’t expect there to be so much iron density at that altitude. It comes from meteors that enter the atmosphere at high speed, burn up and [then] the metal atoms are left suspended. The iron layer is normally a little bit higher. In our case, we hypothesized that on that day there were gravity waves [a wave phenomenon in the air] and the iron layer was lowered,” says Passas Varo. That still sounds like so many different things happening at the right time, but that would also explain their elusive nature and difficulty to capture and study.