This ought to be classified as extraordinary: NASA have recently discovered a – until now – unknown form of space weather that can packs the punch of an earthquake, and plays a key role in sparking bright Northern Lights. They call it “the spacequake.”
“The total energy in a spacequake can rival that of a magnitude 5 or 6 earthquake.”
It rumbles without sound, auroras rain down and the Earth’s magnetic fields starts to shake. This is how NASA Sciense News describes the new form of space weather, recently discovered by the research centers fleet of five THEMIS spacecrafts. The “spacequake” is a temblor in Earth’s magnetic field. It is felt most strongly in Earth orbit, but the effects can reach all the way down to the surface of Earth itself.
“Magnetic reverberations have been detected at ground stations all around the globe, much like seismic detectors measure a large earthquake,” THEMIS principal investigator, Vassilis Angelopoulos of UCLA, says on the NASA Science News website.
It’s an apt analogy because “the total energy in a spacequake can rival that of a magnitude 5 or 6 earthquake,” according to Evgeny Panov of the Space Research Institute in Austria.
Panov is first author of a paper reporting the results in the April 2010 issue of Geophysical Research Letters (GRL).
In 2007, THEMIS discovered the precursors of spacequakes.
A Magnetic Tail Event
The action begins in Earth’s magnetic tail, which is stretched out like a windsock by the million mph solar wind.
Sometimes the tail can become so stretched and tension-filled, it snaps back like an over-torqued rubber band.
Solar wind plasma trapped in the tail then hurtles toward Earth.
On more than one occasion, the five THEMIS spacecraft were in the line of fire when these “plasma jets” swept by.
Clearly, the jets were going to hit Earth. But what would happen then? The fleet moved closer to the planet to find out:
“Now we know,” says THEMIS project scientist David Sibeck of the Goddard Space Flight Center.
“Plasma jets trigger spacequakes.”
A Gas Ball Bouncing
According to THEMIS, the jets crash into the geomagnetic field some 30,000 km above Earth’s equator.
The impact sets off a rebounding process, in which the incoming plasma actually bounces up and down on the reverberating magnetic field. Researchers call it “repetitive flow rebuffing.” It’s akin to a tennis ball bouncing up and down on a carpeted floor.
The first bounce is a big one, followed by bounces of decreasing amplitude as energy is dissipated in the carpet.
“We’ve long suspected that something like this was happening,” says Sibeck. “By observing the process in situ, however, THEMIS has discovered something new and surprising,” he adds.
The surprise is plasma vortices, huge whirls of magnetized gas as wide as Earth itself, spinning on the verge of the quaking magnetic field.
A Noticeable Effect
“When plasma jets hit the inner magnetosphere, vortices with opposite sense of rotation appear and reappear on either side of the plasma jet,” Rumi Nakamura of the Space Research Institute in Austria, a co-author of the study, explains.
“We believe the vortices can generate substantial electrical currents in the near-Earth environment.”
Acting together, vortices and spacequakes could have a noticeable effect on Earth.
The tails of vortices may funnel particles into Earth’s atmosphere, sparking auroras and making waves of ionization that disturb radio communications and GPS.
By tugging on surface magnetic fields, spacequakes generate currents in the very ground we walk on.
Ground current surges can have profound consequences, in extreme cases bringing down power grids over a wide area.
After THEMIS discovered the jets and quakes, Joachim Birn of the Los Alamos National Lab in New Mexico conducted a computer simulation of the rebounding process.
Lo and behold, vortices appeared in good accord with THEMIS measurements.
Moreover, the simulations suggest that the rebounding process can be seen from Earth’s surface in the form of ripples and whirls in auroral displays. Ground stations report just such a phenomenon.
“It’s a complicated process, but it all fits together,” says Sibeck.
A Colonial Mass Put Option?
Personally I can’t help wonder what kind of effect this space-weather-thing will have on the weather derivatives market?
Will we soon be able to buy a colonial mass put option? With a strike magnitude of 5? Expiration date; December 31th 2012?
I’m willing to bet that somewhere, some quant is working on a formula right now…
A Spectacular Fireworks
Right now a thunderstorm with heavy lightning is passing over Oslo, Norway, while the Earth’s magnetic field is still reverberating from the CME impact of August 3rd, which sparked auroras as far south as Wisconsin and Iowa in the United States.
Analysts believe a second CME is not far behind it, due to arrive on today, August 5th, according to spaceweather.com.
A second impact could re-energize the fading geomagnetic storm and spark a new round of Northern Lights.
At the height of the August 3rd display “the whole sky over northern Quebec filled with green and purple,” says photographer Michel Tournay.
“I couldn’t decide where to point my camera!”
Fortunately, he had a wide-angle lens… Have a look at this:
At Ringsaker, outside Oslo in Norway, the auroras were so bright “we could see them through clouds, moonlight and midnight sunlight,” Ragnar Johnskås says.
“It was a lovely show,” he adds.
Indeed it was.
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