A team of researchers from NASA's Goddard Space Flight Center in Greenbelt, Maryland, discovered evidence for an unanticipated role of electrons in creating the pulsating auroras. The unique feature of pulsating auroras is that they shift and brighten in distinct patches unlike active auroras that create elongated arcs across the sky. The team comparing ground-based videos of pulsating auroras with satellite measurements of electrons that fall from Earth’s magnetosphere to the Earth's upper atmosphere. Although electrons cause auroras, it has been assumed that low-energy secondary electrons had no part to play in pulsating auroras. However, the team observed that these secondary electrons “are sent spinning to the surface by complicated wave motions in the magnetosphere” which then creates pulsating auroras. Marilia Samara, the lead author of the study, says, “It turns out that secondary electrons could very well be a big piece of the puzzle to how, why, and when the energy that creates auroras is transferred to the upper atmosphere.”
Read more in Science Daily.