This weekend's solar storm brought spectacular auroras over a big part of the Northern Hemisphere. Here are five facts about these dazzling – and sometimes dangerous – eruptions from our sun.
The sun unleashed a huge flare on Thursday, launching a stream of electrically charged plasma in the direction of Earth at about three million miles per hour. When the solar storm struck our planet's magnetic field on Saturday, it produced a dazzling northern lights display that could be seen as far south as the northern United States.
Here are five key facts about solar storms:
A solar flare is a sudden explosion on the surface of the sun, releasing as much energy as a billion megatons of TNT, according to NASA. (By comparison, the atomic bomb dropped on Hiroshima was equivalent to, at most 0.017 megatons of TNT.)
Most solar flares are accompanied by coronal mass ejections, huge streams of charged plasma that travel at millions of miles per hour.
These coronal mass ejections, when they strike the Earth, can cause moderate to serious geomagnetic storms, disrupting GPS satellites and knocking out power grids.
The CME produced by a February 2011 X-class solar flare, the highest classification, disrupted radio communications in China.