Giant “Magnetic Ropes” from the Sun Power Aurora Borealis

NASA scientists discovered giant "magnetic ropes" that link the Earth’s upper atmosphere to the Sun. Solar wind particles that flow along these ropes provide energy for geomagnetic storms and auroras:

A ‘magnetic rope’ is a twisted bundle of magnetic fields much like a rope made of hemp, and although previous spacecraft have seen glimpses of them, none had been able to map their structure. But the THEMIS’s five identical micro-satellites could, Sibeck told the meeting.

"THEMIS encountered its first magnetic rope on May 20," he said. "It was very large, about as wide as Earth, and located approximately 65,000 km above Earth’s surface in a region called the
magnetopause."

This is the region where solar wind hurtles into the Earth’s magnetic
fields, and magnetic ropes are formed and unfurled in just a few minutes allowing solar wind to be briefly conducted along them.

This enormous burst of energy helps explain the phenomenon of aurora borealis (and its southern hemisphere equivalent, the aurora australis) also known as substorms, said Sibeck.

Link