Magnetic Explosions Draw Scientists Closer to Origin of Northern Lights

[Woodmonkey]

Scientists have exposed some of the mystery behind the northern lights.

On Thursday, NASA released findings that indicate magnetic explosions about one-third of the way to the moon cause the northern lights, or aurora borealis, to burst in spectacular shapes and colors, and dance across the sky.

The findings should help scientists better understand the more powerful but less common geomagnetic storms that can knock out satellites, harm astronauts in orbit and disrupt power and communications on Earth, scientists said.

A fleet of five small satellites, called Themis, observed the beginning of a geomagnetic storm in February, while ground observatories in Canada and Alaska recorded the brightening of the northern lights. The southern lights — aurora australis — also brightened and darted across the sky at the same time.

These auroral flare-ups occur every two or three days, on average.

A team led by University of California, Los Angeles, scientist Vassilis Angelopoulos confirmed that the observed storm about 80,000 miles from Earth was triggered by a phenomenon known as magnetic reconnection. Every so often, the Earth's magnetic field lines are stretched like rubber bands by solar energy, snap, are thrown back to Earth and reconnect, in effect creating a short circuit.

It's this stored-up energy that powers the northern and southern lights or, in other words, causes them to dance, according to Angelopoulos.

An opposing theory has these geomagnetic events occurring much closer to Earth, about one-sixth of the way to the moon. More Themis observations are needed to resolve the debate, said David Sibeck, NASA's project scientist.

"Finally, we have the right instruments in the right place at the right time, and it's allowed scientists to be able to make the necessary observations to settle this heated debate once and for all," said Nicola Fox, a Johns Hopkins University scientist who was not involved in the study.

At present, about 20 of these geomagnetic storms are being analyzed. Scientists hope to eventually learn, via this project, more about the bigger solar storms that occur about 10 times a year and can lead to far more expansive and prolonged northern and southern lights.

The five Themis spacecraft — a NASA acronym standing for Time History of Events and Macroscale Interations during Substorms — were launched aboard a single rocket last year.

The Source

[Snowden]

Scientists Explain Northern Lights

Posted Jul 24, 08 7:01 PM CDT in Science & Health

(Newser) – Scientists say they have solved the mystery of what causes
the dazzling northern lights to seemingly dance across the sky, Wired reports.
The light show, also known as aurora borealis, is triggered by explosions
of magnetic energy about 80,000 miles away. The findings—drawn from
five NASA satellites working in tandem with ground observers—might
help scientists better predict geomagnetic storms that take out satellites.

“We discovered what sparks the magnificent light show of the aurora,”
said one of the scientists. The breakthrough came when satellites detected
the start of a magnetic storm earlier this year. Within minutes, observers
on earth noted that the northern lights began to brighten and fluctuate.


Sources Wired, Times (UK)



A band of Aurora Borealis, the Northern Lights, stretches
over the Chugach Range near Palmer, Alaska, in this file photo.
(AP Photo)

In this Sept. 3, 2006 file photo, a spectator watches the aurora
borealis rise above the Alaska Range, in Denali National Park,
Alaska. (AP Photo/M. Scott Moon, File)

Scientists Explain Northern Lights - Newser