Physics: Shining a light on pulsating aurorae

Insights into the origins of the intense, flickering light displays known as pulsating aurorae are presented in a paper published in this week’s Nature.

Pulsating aurorae are quasi-periodic, blinking patches of light that cover tens to hundreds of kilometres of sky and that appear at an altitude of approximately 100 kilometres in the high-latitude regions of both hemispheres. This pulsation is generated by the intermittent release of energetic electrons into the upper atmosphere. However, no direct evidence of how this release takes place has been reported so far.

Using satellite data collected during an auroral substorm on 27 March 2017, Satoshi Kasahara and colleagues observed that energetic electrons from the magnetosphere are scattered by chorus waves - electromagnetic fluctuations in Earth’s magnetosphere - leading to the precipitation of electrons in the upper atmosphere. The authors suggest that this process may also take place in the aurorae of Jupiter and Saturn, where chorus waves have been detected.