On Aug. 16th, high above a thunderstorm in central Russia, an enormous ring of light appeared in the night sky. Using a low-light video camera in the town of Irbit, amateur astronomer Ilya Jankowsky photographed the 300 km-wide donut hovering near the edge of space:
"It appeared for just a split second, surrounding the horns of Taurus," says Jankowsky.
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 cloud-to-ground lightning propagates up toward space and hits the base of Earth's ionosphere. A faint ring of deep-red light marks the broad 'spot' where the EMP hits.
"For this to happen, the lightning needs to be very strong--typically 150-350 kilo-Ampères," says Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. "For comparison, normal cloud-to-ground flashes only reach 10-30 kA."
ELVEs often appear alongside red sprites, which are also sparked by strong lightning. Indeed, Jankowsky's camera caught at least two clusters of sprites dancing nearby.
ELVEs are elusive--and that's an understatement. Blinking in and out of existence in only a millisecond, 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.
www.spaceweather.com
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 cloud-to-ground lightning propagates up toward space and hits the base of Earth's ionosphere. A faint ring of deep-red light marks the broad 'spot' where the EMP hits.
"For this to happen, the lightning needs to be very strong--typically 150-350 kilo-Ampères," says Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. "For comparison, normal cloud-to-ground flashes only reach 10-30 kA."
ELVEs often appear alongside red sprites, which are also sparked by strong lightning. Indeed, Jankowsky's camera caught at least two clusters of sprites dancing nearby.
ELVEs are elusive--and that's an understatement. Blinking in and out of existence in only a millisecond, 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.
www.spaceweather.com
RSS Feed