Scientists Find the Trigger of the Northern Lights

By KENNETH CHANG
Published: July 25, 2008



Scientists say they have discovered what makes the northern lights dance.

Researchers working on a NASA mission to understand the interplay of magnetic fields and charged particles blown outward from the Sun have identified the trigger for the colorful electrical storms in the polar regions. They hope this is a step in developing reliable forecasts of geomagnetic storms that can disrupt satellites in orbit and power grids on the ground.

The findings appeared in an article published Thursday on the Web site of the journal Science.

Scientists have long known that the dancing auroras of color known as the northern and southern lights are generated by charged particles flying from the Sun and interacting with the Earth’s magnetic field, which is then pulled into a windsock shape by the solar wind.

Turbulent storms on the Sun generate extremely bright auroral displays, but even in quieter times, smaller events known as substorms still generate the lights.

“They happen every three or four hours,” said Vassilis Angelopoulos, a professor of earth and space sciences at University of California, Los Angeles, and principal investigator of a NASA mission called Themis, short for Time, History of Events and Macroscale Interactions during Substorms. “The Earth’s environment stores energy. Then all of a sudden it releases it.”

Each substorm generates a current of about one million to two million amps over one to two hours, or a total energy equivalent to a magnitude-5 or magnitude-6 earthquake, Dr. Angelopoulos said.


More at: The New York Times