NASA determines what puts the "dance" into Northern Lights

William Atkins
Friday, 25 July 2008 01:44

Science - Space

The discovery is important to life here on Earth.

The UCBerkeley article explains, “Substorms often accompany intense space storms that can disrupt radio communications and global positioning system signals and cause power outages. Solving the mystery of where, when, and how substorms occur will allow scientists to construct more realistic substorm models and better predict a magnetic storm's intensity and effects.”

Although these researches with the THEMIS mission have discovered what directly causes the aurora to dance about the northern and southern regions of Earth, the ultimate source is found in the Sun, a star about 93 million miles from the Earth.

The UCBerkeley News articles explains, “The ultimate cause of the aurorae and auroral substorms is the sun, which crackles with flares and violent explosions called coronal mass ejections that send charged particles hurtling into space. When these particles pass by our planet, the particles flow around the Earth along the planet's magnetic field lines and down the "magnetotail" in the shadow of the Earth.”

It continues, “Some of these particles leak into Earth's magnetosphere and arc through the atmosphere toward the poles, colliding with air molecules and making the atmosphere glow like a neon light. From space, the glow is like an oval halo encircling the north and south magnetic poles. Periodically, however, energy builds up in Earth's magnetic field until it breaks, releasing a sudden burst of electrical current into the atmosphere that turns the green aurora purple, red and white and make it shimmy and shake.”

The THEMIS team's findings appears in the article "Tail Reconnection Triggering Substorm Onset" online July 24, 2008, in Science Express, the early version of Science, and August 14, 2008 in the journal Science.

The paper's authors are: Vassilis Angelopoulos, James P. McFadden, Davin Larson, Charles W. Carlson, Stephen B. Mende, Harald Frey, Tai Phan, David G. Sibeck, Karl-Heinz Glassmeier, Uli Auster, Eric Donovan, Ian R. Mann, I. Jonathan Rae, Christopher T. Russell, Andrei Runov, Xu-Zhi Zhou, and Larry Kepko.

For more information about the THEMIS mission, visit “THEMIS at NASA.”

NASA has extended the THEMIS mission to the year 2012. Additional information about the THEMIS mission is found at NASA’s website, "THEMIS: Understanding Space Weather.”l