Scientists Discover 'Space Weather' Behind Dazzling Northern Lights

Solar storms can be powerful as solar material and magnetic fields erupt into interplanetary space. Known as "space weather," these storms can impact satellites and even cause power blackouts on Earth. Now, scientists have taken a closer look at space weather, showing exactly what causes it.

During solar storms, the sun can emit vast amounts of energy. Some of that energy, though, is temporarily stored in Earth's stretched and compressed magnetic field. Eventually, the solar energy is explosively released and powers Earth's radiation belts, lighting up the polar skies with brilliant auroras. The invisible process that releases this stored magnetic energy, though, has defied observation for decades.

Now, scientists have gotten a closer look at this phenomenon. They've measured the release of this energy using an unprecedented alignment of six Earth-orbiting spacecraft and NASA's first dual lunar orbiter mission, ARTEMIS. These observations didn't come easy, though.

Space weather begins to develop inside Earth's magnetosphere, the giant magnetic bubble that shields our planet from the supersonic flow of magnetized gas emitted from the sun. During solar storms, some solar energy enters the magnetosphere and stretches this bubble. Eventually, the stored magnetic energy is released in a process called "magnetic reconnection." Yet the event can only be detected when fast flows of energized particles pass by a spacecraft positioned at exactly the right place at the right time.

Fortunately for the researchers, an alignment among THEMIS, ARTEMIS and the Japanese Space Agency's Geotail satellite and the NOAA's GOES satellite managed to capture data accounting for the total amount of energy that drives space weather near Earth. A tremendous amount of energy was released during this particular event.

"The amount of power converted was comparable to the electric power generation from all power plants on Earth-and it went on for over 30 minutes," said Vassilis Angelpoulos, one of the researchers, in a news release. "The amount of energy released was equivalent to a 7.1 Richter-scale earthquake."

In other words, the researchers found exactly what powers Earth's aurora and radiation belts. Knowing the total amount of energy involved is crucial for future research. Now, the scientists can focus their attention on the physics of the energy conversion and its eventual dissipation in order to improve space weather forecasts.

"It's a very exciting time ahead," said David Sibeck, one of the researchers, in a news release. "Never before did we have the possibility for so many high-quality observations lining up."

The findings are published in the journal Science.