Using data from NASA’s Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites, scientists have observed Earth’s vibrating magnetic field in relation to the northern lights in the night sky over Canada. THEMIS is a five-spacecraft mission dedicated to understanding the processes behind auroras, which erupt across the sky in response to changes in Earth’s magnetosphere.
These new observations allowed scientists to directly link specific intense disturbances in the magnetosphere to the magnetic response on the ground. A paper on these findings was recently published in Nature Physics.
To map the auroras’ electric dance, scientists imaged the brightening and dimming aurora over Canada with all-sky cameras. They simultaneously used ground-based magnetic sensors across Canada and Greenland to measure electrical currents during the geomagnetic substorm. Further out in space, the five THEMIS probes were positioned to collect data on the motion of the disrupted field lines.
The scientists found the aurora moved in harmony with the vibrating field line. Magnetic field lines oscillated in a roughly six-minute cycle, or period, and the aurora brightened and dimmed at the same pace.
“We were delighted to see such a strong match,” said Evgeny Panov, lead author and researcher at the Space Research Institute of the Austrian Academy of Sciences in Graz. “These observations reveal the missing link in the conversion of magnetic energy to particle energy that powers the aurora.”
An artist’s rendering (not to scale) describes a cross-section of the magnetosphere, with the solar wind in yellow and magnetic field lines emanating from Earth in blue. The five THEMIS probes were positioned to directly observe one particular magnetic field line as it oscillated back and forth every six minutes. (Credit: Emmanuel Masongsong/UCLA EPSS/NASA)