Boffins discover “spacequakes” that rumble in Earth’s atmosphere

August 2nd, 2010 - 1:12 pm ICT by ANI  

National Geographic Washington, Aug 2 (ANI): Scientists using NASA’s THEMIS mission have come across a new form of space weather. They have dubbed it a “spacequake”

A spacequake - a strong vibration in the planet’s magnetic field - can affect auroras and generate “space twisters” powerful enough to bring down power lines.

In general, Earth’s magnetic field lines can be thought of as rubber bands stretched taut by the solar wind, which is actually charged particles flowing in all directions from the sun, said study co-author Vassilis Angelopoulos, a space physicist at the University of California, Los Angeles.

Earth’s magnetic tail is the part of the field that’s stretched out like a windsock by the sun’s steady bombardment.

New data from NASA’s fleet of five THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft shows that, when a magnetic field line in the tail builds up too much energy, it snaps, and part of the line is sent hurtling back toward Earth.

In the process, the broken line can attract high-energy particles in Earth’s atmosphere to create a whip-like “plasma jet.”

These jets crash into other parts of Earth’s magnetic field at about 32,000 km above the planet’s surface, where they bounce like tennis balls hitting a carpet.

“We have learned that the plasma jets from the magnetic tail bounce and then bounce again, and so on, till they eventually lose all their energy,” National Geographic quoted Angelopoulos, also the principal investigator for THEMIS, as saying.

Each set of plasma jet impacts can release as much energy in total as a magnitude 5 to 6 earthquake, THEMIS revealed.

Furthermore, the impacts set Earth’s entire magnetic field vibrating, and they create highly magnetic vortices, or space twisters, that penetrate down into the planet’s atmosphere.

These vortices twirl Earth’s magnetic field lines in the North and South Poles, where they can create bright ripples and whirls in auroras.

The effects of the vortices can even be felt on the Earth’s surface, as they can induce current spikes in electrical lines that can bring down power grids over large areas.

The study has been published in the April issue of the journal Geophysical Research Letters. (ANI)

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