Northern Lights Mystery

According to a new study the electrons responsible for the auroras, also known as the northern lights, are likely accelerated to incredible speeds in an active region of Earth’s magnetosphere.

This region is 1,000 times larger than scientists had thought possible, providing enough volume to generate lots of the fast-moving electrons. Researchers analyzed data gathered by various spacecraft, including the European Space Agency’s four Cluster probes. They also performed simulations using a supercomputer called Kraken at the United States Department of Energy’s Oak Ridge National Laboratory in Tennessee. Kraken has 112,000 processors working in parallel. The team used 25,000 of these processors for 11 days, following the motions of 180 billion simulated particles in space to map out how aurora-generating electrons move. The researchers determined that these electrons are likely being rocketed to their tremendous speeds in the magnetotail, a portion of Earth’s protective magnetosphere that has been pushed far into space by the solar wind. As the solar wind stretches Earth’s magnetic-field lines, the field stores energy like a rubber band being stretched. When the normally parallel field lines reconnect, that energy is released like a rubber band being snapped, and electrons are propelled back toward our planet at fantastic speeds. When these fast-moving electrons hit molecules in Earth’s upper atmosphere, the impact generates the phenomenon that we know as the northern lights, according to Jan Egedal, of the Massachusetts Institute of Technology.