On June 8th, high above a thunderstorm in Colorado, an enormous ring of light appeared near the edge of space. Amateur astronomer Thomas Ashcraft photographed the phenomenon using a low-light video camera.
"It only lasted about a millisecond," says Ashcraft, "but it was definitely there. The ring was about 300 km wide," he estimates.
This is an example of an ELVE (Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources). First seen by cameras on the space shuttle in 1990, ELVEs appear when a pulse of electromagnetic radiation from lightning propagates up toward space and hits the base of Earth's ionosphere. A faint ring of light marks the broad 'spot' where the EMP hits.
ELVES often appear alongside red sprites. Indeed, Ashcraft's camera caught a cluster of sprites leaping straight up through the middle of the donut. "Play the complete video (below) to see the sprites," says Ashcraft.
ELVEs are elusive--and that's an understatement. Blinking in and out of existence in only 1/1000th of a second, they are completely invisible to the human eye. For comparison, red sprites tend to last for hundredths of a second and regular lightning can scintillate for a second or more. Their brevity explains why ELVEs are a more recent discovery than other lightning-related phenomenon.
Learn more about the history and physics of ELVEs here and here.