Brushfires in the Sky: "The electrons and protons that rain down on our atmosphere to produce colorful Northern Lights don't come directly from the solar wind. Instead, they follow a more circuitous route through the 'magnetotail.'

The magnetotail is an area of space behind the night side of Earth where the solar wind stretches the magnetic field into a long comet-like tail. Inside the magnetotail is the 'plasma sheet,' a region that's densely populated with ionized gas. Although it's more than 60,000 km away, what happens in the plasma sheet is crucial to auroral activity.

When an energetic burst of solar particles strikes the magnetosphere, it compresses the magnetic field and stretches the magnetotail more than normal. This causes neighboring magnetic field lines with opposite polarities to connect inside the plasma sheet. Intense electric fields created by this magnetic reconnection launch plasma toward the Earth's north and south magnetic poles where it strikes the atmosphere, triggering aurora in a circular line called the auroral oval."