NASA Pinpoints Driving Force Behind Auroral Arcs

NASA scientists have identified a potential driving force behind auroral arcs, a specific type of aurora. This discovery was made by reviewing archived observations of the phenomenon.

Understanding Auroral Arcs

Auroras are natural light displays that occur when charged particles from space collide with Earth’s upper atmosphere, forming colored patterns across the sky. Auroral arcs, a distinct type of aurora, appear as glowing curtains of light from the ground and as thin green lines when viewed from space.

Alfvén Waves: The Power Source

Auroral arcs are generated when high-energy electrons in space impact atoms in Earth’s upper atmosphere, releasing light. This process is powered by electric fields in space.

Research findings indicate that these electric fields are powered by a type of space wave known as Alfvén waves, which travel along Earth’s magnetic field lines.

Data from Multiple Viewpoints

The findings are based on a simultaneous observation of an auroral arc conducted in April 2015. This observation utilized three instruments: NASA’s Van Allen Probes, the U.S. military’s Defense Meteorological Satellite Program F19 spacecraft, and ground-based cameras from NASA’s THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission.

A Comprehensive Understanding

The combined data from these instruments offered multiple viewpoints of the same event over an extended period. This comprehensive perspective assisted scientists in understanding the space conditions that contribute to the formation of auroral arcs.