A Giant Breach in Earth's Magnetic Field

Dec. 16, 2008: NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist. Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms. But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.

"At first I didn't believe it," says THEMIS project scientist David Sibeck of the Goddard Space Flight Center. "This finding fundamentally alters our understanding of the solar wind-magnetosphere interaction."

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stoke said:

So, the effects of a massive geomagnetic storm could include:
- Pigeons and Dolphins and other animals what work on the gravity waves will get lost
- Shortwave radio will be impossible
- Some cables may induce more electricity into them than normal, really long copper cables could be induced into carrying large voltages.
- and some other stuff ...
Actually .. what's the risk really?

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stoke said:

So, the effects of a massive geomagnetic storm could include:
- Pigeons and Dolphins and other animals what work on the gravity waves will get lost
- Shortwave radio will be impossible
- Some cables may induce more electricity into them than normal, really long copper cables could be induced into carrying large voltages.
- and some other stuff ...
Actually .. what's the risk really?

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marine1 said:

The world is already dilly.

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stoke said:

Quick .. buy shares in companies that make tinfoil!
I've already got my 20 rolls!

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ScienceDaily (Dec. 17, 2008) — Earth's magnetic field, which shields our planet from particles streaming outward from the Sun, often develops two holes that allow the largest leaks, according to researchers sponsored by NASA and the National Science Foundation.

"The discovery overturns a long-standing belief about how and when most of the solar particles penetrate Earth's magnetic field, and could be used to predict when solar storms will be severe. Based on these results, we expect more severe storms during the upcoming solar cycle," said Vassilis Angelopoulos of the University of California, Los Angeles, Principal Investigator for NASA's THEMIS mission (Time History of Events and Macroscale Interactions during Substorms). THEMIS was used to discover the size of the leak.

Earth's magnetic field acts as a shield against the bombardment of particles continuously streaming from the sun. Because the solar particles (ions and electrons) are electrically charged, they feel magnetic forces and most are deflected by our planet's magnetic field. However, our magnetic field is a leaky shield and the number of particles breaching this shield depends on the orientation of the sun's magnetic field. It had been thought that when the sun's magnetic field is aligned with that of the Earth, the door is shut and that few if any solar particles enter Earth's magnetic shield. The door was thought to open up when the solar magnetic field direction points opposite to Earth's field, leading to more solar particles inside the shield.

Surprisingly, recent observations by the THEMIS spacecraft fleet demonstrate that the opposite is true. "Twenty times more solar particles cross the Earth's leaky magnetic shield when the sun's magnetic field is aligned with that of the Earth compared to when the two magnetic fields are oppositely directed," said Marit Oieroset of the University of California, Berkeley, lead author of one of two papers on this research, published May 2008 in Geophysical Research Letters.

Researchers have long suspected that this "closed door" entry mechanism might exist, but didn't know how important it was. "It's as if people knew there was a crack in a levy, but they did not know how much flooding it caused," said Oieroset.

Previous spacecraft could only sample a small part of this enormous layer of solar particles inside the Earth's magnetic shield, but the five spacecraft in the THEMIS fleet spanned the entire rapidly-growing layer to give definitive measurements.

While the THEMIS researchers discovered the size of the leak, they didn't know its location(s). This was discovered by Wenhui Li of the University of New Hampshire, Durham, N.H., and his team. They used a computer simulation to discover where two holes frequently develop in Earth's magnetic field, one at high latitude over the Northern hemisphere, and one at high latitude over the Southern hemisphere. The holes form over the daylit side of Earth, on the side of the magnetic shield facing the sun.

The simulation also showed how the leaks develop. As solar particles flow out from the sun, they carry solar magnetic fields past our planet. Li's team realized that the solar magnetic field drapes against Earth's field as it passes by. Even though the two fields point in the same direction at equatorial latitudes, they point in opposite directions at high latitudes, When compression forces the opposite fields together, they link up with each other in a process called magnetic reconnection.

This process tears the two holes in Earth's magnetic field and appends the section of the solar field between the two holes to Earth's field, carrying the solar particles on this section into the magnetosphere, according to Li's team. "We've found if the door is closed, the sun tears down a wall. The crack is huge – about four times wider than Earth and more then seven Earth diameters long," said Li, whose paper will be published in an upcoming article of the Journal of Geophysical Research.

Solar particles by themselves don't cause severe space weather, but they get energized when the solar magnetic field becomes oppositely-directed to Earth's and reconnects in a different way. The energized particles then cause magnetic storms that can overload power lines with excess current, causing widespread blackouts. The particles also can cause radiation storms that present hazards to spacecraft in high orbits and astronauts passing through the storms on the way to the moon or other destinations in the solar system.

"The more particles, the more severe the storm," said Joachim "Jimmy" Raeder of the University of New Hampshire, a co-author of Li's paper. "If the solar field has been aligned with the Earth's for a while, we now know Earth's field is heavily loaded with solar particles and primed for a strong storm. This discovery gives us a basic predictive capability for the severity of solar storms, similar to a hurricane forecaster's realization that warmer oceans set the stage for more intense hurricanes. In fact, we expect stronger storms in the upcoming solar cycle. The sun's magnetic field changes direction every cycle, and due to its new orientation in the upcoming cycle, we expect the clouds of particles ejected from the sun will have a field which is at first aligned with Earth, then becomes opposite as the cloud passes by."

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dam said:

The destruction of cellular tissue, which means that we will all be toast.

Edit: Just read further and it looks like the magnetosphere doesn't protect us from that kind of radiation so we are safe for now.

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alf101 said:

So this has been happening since the beginning of time, and we just noticed it.

Very scary?

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stoke said:

Thanks Wiz.
So .. lava surfing is going to be a bit more tricky soon

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alf101 said:

So this has been happening since the beginning of time, and we just noticed it.

Very scary?

Click to expand...

Scientists have found two large leaks in Earth's magnetosphere, the region around our planet that shields us from severe solar storms.

The leaks are defying many of scientists' previous ideas on how the interaction between Earth's magnetosphere and solar wind occurs: The leaks are in an unexpected location, let in solar particles in faster than expected and the whole interaction works in a manner that is completely the opposite of what scientists had thought.

The findings have implications for how solar storms affect the our planet. Serious storms, which involved charged particles spewing from the sun, can disable satellites and even disrupt power grids on Earth.

The new observations "overturn the way that we understand how the sun's magnetic field interacts with the Earth's magnetic field," said David Sibeck of NASA's Goddard Space Flight Center in Greenbelt, Md., during a press conference today at the annual meeting of the American Geophysical Union in San Francisco.

The bottom line: When the next peak of solar activity comes, in about 4 years, electrical systems on Earth and satellites in space may be more vulnerable.

How it works

Earth's magnetic field carves out a cavity in the sun's onrushing field. The Earth's magnetosphere is thus "buffeted like a wind sock in gale force winds, fluttering back and forth in the" solar wind, Sibeck explained.

Both the sun's magnetic field and the Earth's magnetic field can be oriented northward or southward (Earth's magnetic field is often described as a giant bar magnet in space).

The sun's magnetic field shifts its orientation frequently, sometimes becoming aligned with the Earth, sometime becoming anti-aligned.

Scientists had thought that more solar particles entered Earth's magnetosphere when the sun's field was oriented southward (anti-aligned to the Earth's), but the opposite turned out to be the case, the new research shows.

The work was sponsored by NASA and the National Science Foundation and based on observations by NASA's THEMIS (Time History of Events and Macroscale Interactions during Substorms) satellite.

How many and where

Essentially, the Earth's magnetic shield is at its strongest when scientists had thought it would be at its weakest.

When the fields aren't aligned, "the shield is up and very few particles come in," said physicist Jimmy Raeder of the University of New Hampshire in Durham.

Conversely, when the fields are aligned, it creates "a huge breach, and there's lots and lots of particles coming in," Raeder added, at the news conference.

As it orbited Earth, THEMIS's five spacecraft were able to estimate the thickness of the band of solar particles coming when the fields were aligned — it turned out to be about 20 times the number that got in when the fields were anti-aligned.

THEMIS was able to make these measurements as it moved through the band, with two spacecraft on different borders of the band; the band turned out to be one Earth radius thick, or about 4,000 miles (6,437 kilometers).

Measurements of the thickness taken later showed that the band was also rapidly growing.

"So this really changes our understanding of solar wind-magnetosphere coupling," said physicist Marit Oieroset of the University of California, Berkeley, also at the press conference.

And while the interaction of anti-aligned particles occurs at Earth's equator, those of aligned particles occur at higher latitudes both north and south of the equator.

The interaction is "appending blobs of plasma onto the Earth's magnetic field," which is an easy way to get the solar particles in, said Sibeck, a THEMIS project scientist.

Next solar cycle

This finding not only has implications for scientists' understanding of the interaction between the sun and Earth's magnetosphere, but for predicting the effects to Earth during the next peak in the solar cycle.

The Sun operates on an 11-year cycle, alternating between active and quiet periods. We are currently in a quiet period, with few sunspots on the sun's surface and fewer solar flares, though the next cycle of activity has begun.

It is expected to peak around 2012, bringing lots of sunspots, flares and coronal mass ejections (CMEs). CMEs can interact with the Earth's magnetosphere, causing problems for satellites, communications, and power grids.

This upcoming active period now looks like it will be more intense than the previous one, which peaked around 2006, some scientists think. The reason is the changes in the sun's alignment.

During the last peak, solar fields hitting the Earth were first anti-aligned then aligned. Anti-aligned fields can energize particles, but in this case, the energy came before the particles themselves, which doesn't create much of a fuss in terms of geomagnetic storms and disruptions.

But the next cycle will see aligned, then anti-aligned fields, in theory amplifying the effects of the storms as they hit.

Raeder likens the difference to igniting a gas stove one of two ways: In the first way, the gas is turned on and the stove is lit and you get a flame.

In the other way, you let the gas run for awhile, so that when you add the gas you get a much bigger boom.

"It should be that we're in for a tough time in the next 11 years," Sibeck said.

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