New mapping in Australia has revealed a strange dent in the magnetic field beneath the country's Northern Territory.

The Australia Magnetic Anomaly, named after its similarity in shape to the country, holds valuable information about Australia's geological history, including how different rock layers formed and acquired their distinctive magnetic properties.

"Magnetic data allows us to see through the ground and understand geological architecture that would otherwise remain completely hidden," project lead Clive Foss, a senior research geoscientist with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), said in a statement.

A magnetic anomaly is a local variation in Earth's magnetic field caused by the magnetic properties of certain minerals and rocks, such as iron ore deposits, in the crust.

From the moment they form, rocks start to develop magnetic signatures that incorporate information about the direction of Earth's magnetic field at that specific time. This "magnetic memory," known as remanent magnetism, helps scientists reconstruct rocks' past.

However, the magnetic field occasionally flips, and tectonic processes can change rocks' orientation, which muddles the picture. But if scientists can decipher the various clues encrypted in a rock's magnetic signature, they can reconstruct exactly what the rock went through and when.

The Australia Magnetic Anomaly contains structures such as faults, folds and basins that traditional mapping techniques haven't been able to detect, according to the statement. To explore these hidden layers, Foss and his team used advanced modeling techniques to better visualize magnetic data collected during the Northern Territory Government's 1999 Bonney Well Survey.

For that survey, planes fitted with magnetometers — instruments that measure magnetic fields — flew across the Northern Territory in regular lines separated by about 1,300 feet (400 meters). Scientists previously tried to map these data, but the maps didn't always render magnetic signals clearly — particularly along the flight lines, according to the statement.

The new modeling has solved this problem. "My colleague, Dr Aaron Davis, created an innovative gridding algorithm which refined the dataset and produced cleaner, more consistent images," Foss said. "By improving how we process and model these datasets, we can extract more geological information than ever before."

The researchers identified subtle magnetic layers, as well as buried geological boundaries and structures that previous mapping didn't pick up.

The team is still working to interpret these findings, but preliminary results show that the western margin of the Australia Magnetic Anomaly is exposed at the surface in the Northern Territory's Hatches Creek Formation — a geological unit composed of sandstones and volcanic rocks that were deposited between 2.5 billion and 1.6 billion years ago.

Ultimately, mapping the Australia Magnetic Anomaly could lead to important geological discoveries, including opportunities for resource exploration, according to the statement. Companies and Australia's government could benefit from research that creates more detailed maps of mineral deposits.

In 2008, Erez Ben-Yosef unearthed a piece of Iron Age "trash" and inadvertently revealed the strongest magnetic-field anomaly ever found.

Ben-Yosef, an archaeologist at Tel Aviv University, had been working in southern Jordan with Ron Shaar, who was analyzing archaeological materials around the Levant. Shaar, a geologist at The Hebrew University of Jerusalem, was building a record of the area's magnetic field.

The hunk of copper slag — a waste byproduct of forging metals — they found recorded an intense spike in Earth's magnetic field around 3,000 years ago.

When Ben-Yosef's team first described their discovery, many geophysicists were skeptical because the magnitude of the spike was unprecedented in geologic history. "There was no model that could explain such a spike," Ben-Yosef told Live Science.

Related: Major 'magnetic anomaly' discovered deep below New Zealand's Lake Rotorua

So Shaar worked hard to give them more evidence. After they had analyzed and described samples from around the region for more than a decade, the anomaly was accepted by the research community and named the Levantine Iron Age Anomaly (LIAA). From about 1100 to 550 B.C., the magnetic field emanating from the Middle East fluctuated in intense surges.

Shaar and Ben-Yosef were using a relatively new technique called archaeomagnetism. With this method, geophysicists can peer into the magnetic particles inside archaeological materials like metal waste, pottery and building stone to recreate Earth's magnetic past.

This technique has some advantages over traditional methods of reconstructing Earth's magnetic field, particularly for studying the relatively recent past.

Generally, scientists study Earth's past magnetic field by looking at snapshots captured in rocks as they cooled into solids. But rock formation doesn't happen often, so for the most part, it gives scientists a glimpse of Earth's magnetic field hundreds of thousands to millions of years ago, or after relatively rare events, like volcanic eruptions. Past magnetic-field data helps us understand the "geodynamo" — the engine that generates our planet's protective magnetic field. This field is generated by liquid iron slowly moving around the planet’s outer core, and this movement can also affect, and in turn be affected by, processes in the mantle, Earth's middle layer. So differences in the magnetic field hint at turmoil roiling deep below the surface in Earth's geodynamo.

"We cannot directly observe what is going on in Earth's outer core," Shaar told Live Science. "The only way we can indirectly measure what is happening in the core is by looking at changes in the geomagnetic field."

Knowing what the magnetic field did in the past can help us predict its future. And some studies suggest our planet's magnetic field is weakening over time. The magnetic field shields us from deadly space radiation, so its weakening could lead to a breakdown in satellite communications, and potentially increase cancer risk. As a result, predicting the magnetic field based on its past behavior has become ever more important. But observational data of the magnetic field’s intensity only began in 1832, so it's difficult to make predictions about the future if we only dimly understand the forces that steered the magnetic field in the past. Archaeomagnetism has started to fill these gaps.

How do we see the magnetic field from an archaeological artifact?

Archaeomagnetism takes advantage of our human ancestors' harnessing of the earth around them — they started building firepits, making bricks and ceramics, and eventually, smelting metals.

In each of these tasks, materials are heated to intense temperatures. At high enough temperatures, thermal energy makes the particles inside a material dance around. Then, as the material is removed from the fire and cools, the magnetically sensitive particles inside naturally orient in the direction of Earth's magnetic field, like miniature compass needles. They become "stuck" in place as the material hardens, and will retain this magnetic orientation unless the material is heated again.

The settled magnetic particles in an archaeological artifact offer a unique snapshot of the magnetic field at the time the material was last hot. This snapshot is regional, spanning a radius of about 310 miles (500 kilometers) around the sample — the scale at which the magnetic field is thought to be uniform, Shaar said. When the sample is dated with radiocarbon or other techniques, scientists can begin to build a chronological record of an area's magnetic field.

These artifacts are so helpful for geophysicists because Earth's magnetic field constantly drifts. For instance, in 2001, the magnetic north pole was closer to the very northern tip of Canada, but by 2007, it had moved over 200 miles (320 km) closer to the geographic north pole. That's because two large "lobes" of strong magnetism, called flux patches, in the outer core underneath Canada and Siberia act as funnels for the magnetic field, pulling it into Earth. As these lobes shift, they move magnetic north.

And while most of the planet's magnetic-field lines go from north to south, about 20% diverge from these paths, swirling to form eddies called magnetic anomalies.

It's these anomalies that researchers are struggling to explain, and that artifacts could reveal.

A growing field

Although archaeomagnetism has been around since the 1950s, magnetic-field-measuring technologies, like the magnetometer, have improved dramatically since then. Refined statistical analysis techniques also now allow much more detailed interpretation of archaeomagnetic data.

To get all of the data in one place and synthesize our understanding of Earth's magnetic field, scientists have started to build a global database called Geomagia50, hosted at the University of Minnesota's (UM) Institute for Rock Magnetism. But even as the technique grows in popularity, there are many hurdles to widespread adoption.

"The equipment is quite expensive," Maxwell Brown, a UM geophysicist and custodian of the Geomagia50 database, told Live Science. The most precise magnetometers can cost between $700,000 and $800,000, Brown said. "So there are only a few labs in the [United States] that have one of these."

As a result, about 90% of the data in the Geomagia50 database has come from Europe, Brown said. Africa doesn't have a single magnetometer available to geophysicists for archaeomagnetic sampling, meaning our magnetic snapshot of the continent is largely blank. Additionally, there are no current avenues for the average archaeologist to send their artifacts to be sampled, Ben-Yosef added. Anyone without a magnetometer has to set up an official partnership with someone who does have one.

Even if the equipment is available, sampling takes time and expertise, Shaar said. Measuring the direction of the field can sometimes be relatively simple, but understanding the intensity of the field takes much more work. The sample must be heated and reheated 20 separate times, gradually replacing the original magnetization and destroying the sample.

"It sounds like it's an easy thing: We put it in a magnetometer or instrument, and we get the results. No. For each artifact, we spend two months working in the lab, making experiments and then getting the results. It's a complicated, experimental procedure," Shaar explained.

This lack of global data limits our understanding of what the magnetic field has been up to in recent history. "We clearly have a very strong bias [toward Europe] in the data distribution," Monika Korte, a geophysicist and magnetic modeler at Germany's GFZ Helmholtz Centre for Geosciences, told Live Science. "Where we have sparse data we have just a very blurred picture, a very rough idea of what's going on."

Geographic diversity is important, as samples taken from one area can indicate the magnetic field only in that area.

For instance, other data similar to the Levantine Iron Age Anomaly's intense spikes of magnetic strength have been spotted in places like China and Korea around the Iron Age as well, but there's not enough evidence to confirm these as bona fide anomalies or to say whether they are related to the Levantine Iron Age Anomaly, Korte said.

Why should we learn more about historic anomalies?

The discovery of the Levantine Iron Age Anomaly redefined our previous understanding of the potential strength of the field, Shaar said. Understanding how much the magnetic field can change may seem like a purely abstract endeavor, but these ancient fluctuations may have implications for modern times.

Another important anomaly is the South Atlantic Anomaly (SAA), a region of weakened magnetic field that spans central South America in a strip that ends near southern Africa. It likely first emerged 11 million years ago, caused by the slight difference in location of the magnetic axis and the rotational axis at Earth’s core. As the magnetic field is slightly off-center to the rotational axis, the field dips in strength over the South Atlantic, though the field's interaction with the churning mantle may also contribute to the anomaly.

The South Atlantic Anomaly still exists today, and has disrupted communications from satellites and the International Space Station, as the weak magnetic field in the region lets through more radiation from solar wind. Studying the SAA throughout its history has helped scientists understand how our magnetic field changes over time, and how such anomalies alter the likelihood of a magnetic field reversal, when Earth’s north and south poles flip.

But although scientists have a reasonable understanding of the South Atlantic Anomaly, its weakened magnetic field is very different from the strong spikes of the Levantine Iron Age Anomaly, which has baffled geophysicists. And though researchers haven't pinpointed the exact extent of the anomaly, its seemingly small scale of around 1,000 miles (1,609 km) across, combined with the extremely high spikes in the magnetic field, isn't easily explained.

Some geomagnetists had suggested that the Levantine Iron Age Anomaly developed due to a narrow flux patch that developed on the outer core under the equator before it drifted north towards the Levant, potentially contributing to other spikes of intensity recorded in China. The inverse of the large lobes that funnel the magnetic field into the planet at the North Pole, this “positive” flux patch would have pushed the field out in a powerful burst. Others believed the single flux patch didn’t travel, instead multiple grew under the Levant, erupted, and decayed in place. Still, no theories can explain why the flux patch developed in the first place.

With the most up-to-date archaeomagnetic data, geomagnetist Pablo Rivera at the Complutense University of Madrid published a paper in January that simulated both the Levantine Iron Age Anomaly and the South Atlantic Anomaly. By modeling their movement over time, his work suggested that both anomalies may have been influenced by a superplume underneath Africa — a massive blob of hot rock on the barrier between the core and the mantle that may disrupt the flow of the geodynamo below it.

However, much is still unknown.

"So far, there is not a single simulation that really describes all the [magnetic] features that we see well," Korte told Live Science.

Many archaeomagnetic data points from around the globe suggest there may be more intensity spikes that could help resolve the mystery and create a unifying theory to explain the SAA, the LIAA and other spikes. But there currently isn’t enough data to describe them accurately, or even begin to understand their causes.

"We don't really understand what causes these anomalies, but we hope to learn more about how the geodynamo operates and what kinds of changes we also can expect for the future magnetic field," Korte said.

This certainty is needed now more than ever, as more of our communications take to the skies. More than 13,500 satellites currently orbit Earth — a dramatic increase from only around 3,000 in 2020. The Government Accountability Agency estimates that another 54,000 satellites will launch by 2030. These satellites monitor weather patterns, send phone and TV signals, and create GPS.

Satellites are generally protected from space radiation by Earth's magnetic field. But in places where the field is weaker, such as above the South Atlantic Anomaly, satellites have more memory problems as radiation bombards onboard computers and corrupts data.

Filling out the picture

Despite the expense and technical challenges of archaeomagnetism, there are many initiatives to expand the amount of data. In the U.S., the Institute for Rock Magnetism is expanding its archaeomagnetism program to begin building a more thorough history of the magnetic field in the Midwest, hoping to build their own localized dating system using archaeomagnetism, similar to the record Shaar and his collaborators have built in the Levant.

Interest in archaeomagnetism is also growing around the globe. The first archaeomagnetism data from Cambodia was published in 2021, and the first regional model of the magnetic field of Africa for the recent past was published in 2022.

As the field of archaeomagnetism grows, scientists can start building a better understanding of how features like superplumes affect the magnetic field. The past 50 or so years of data has captured "only a really tiny snapshot in time," Shaar said, and "maybe there are more [anomalies] to find."

Earth's magnetic field and oxygen levels are inextricably linked, new research suggests.

The strength of the geomagnetic field has gone up in lockstep with the percentage of oxygen in Earth's atmosphere over the past 540 million years, a new study finds — but it remains unclear if one of these influences the other, or whether other unknown factors explain the link.

"This is the first discovery we've ever had to establish the link between the geomagnetic field and the oxygen level," lead author Weijia Kuang, a senior scientist in the Geodesy and Geophysics Laboratory at NASA's Goddard Space Flight Center, told Live Science.

Earth's magnetic field and oxygen levels have increased more or less in parallel since the start of the Cambrian period (541 million to 485.4 million years ago), and both factors spiked between 330 million and 220 million years ago, the results indicate.

The research could help to narrow down requirements for life on other planets, Kuang and study co-author Ravi Kopparapu, a planetary scientist at the NASA Goddard Space Flight Center, said in a joint video interview.

It may be that the geomagnetic field controls oxygen levels, or vice versa — but there is another possible scenario, which is that both factors are related to a third geochemical or geophysical process that the researchers haven't yet pinpointed, Kuang said.

For the new study, scientists used two independent datasets spanning the past 540 million years. One of the datasets showed atmospheric oxygen, derived from multiple indicators such as the abundance in sediments of fossilized charcoal, which remains after wildfires and gives clues about how much oxygen was available at a given time. The other dataset showed the strength of the geomagnetic field, derived from magnetic information that is recorded in ancient rocks and sediments. The researchers plotted these datasets against each other and found there was a strong correlation between them.

If the geomagnetic field controls oxygen levels, its influence would likely be due to the protection it offers Earth's atmosphere against space weather. Previous research indicates that the geomagnetic field can prevent or reduce the escape or erosion of atmospheric molecules. The magnetic field also shields life on the planet, including plants that produce oxygen, from X-ray and extreme ultraviolet radiation.

If, in contrast, atmospheric oxygen levels dictate the strength of Earth's magnetic field, then plate tectonics would play a central role. Plate tectonics is the process that continuously recycles Earth's crust into the mantle, which is the planetary layer that covers Earth's liquid outer core.

Earth's geomagnetic field originates from currents in the outer core, so it's possible that the recycling of crustal material and oxygen into the mantle could impact the lower mantle, which could then affect the geomagnetic field, Kuang said.

Related: Did plate tectonics give rise to life? Groundbreaking new research could crack Earth's deepest mystery.

"Plate tectonics [...] will definitely impact the thermal and the dynamical conditions at the base of the mantle where it borders the liquid outer core," he said. "On the other hand, plate tectonics also impacts the cycling of chemicals and other elements from the interior to the surface, which certainly will impact oxygenation, or the production of oxygen."

It's more likely that the geomagnetic field affects oxygen levels, rather than the other way round, Kuang said. That's because scientists know the geomagnetic field originates deep inside the planet and propagates to Earth's surface and into space. "The other direction is less well understood," he said.

The third possible scenario is that another, separate process is pushing the geomagnetic field and oxygen levels in the same direction over time. The study's authors don't know what that process might be yet, but a spike that exists in both datasets may hold the answer.

'A very enticing mechanism'

The spike coincides with the existence of the ancient supercontinent Pangaea, which formed about 320 million years ago and broke up about 195 million years ago. Due to the massive tectonic rearrangements involved, supercontinents might be the missing link between Earth's magnetic field and oxygen levels — but the evidence for this is still very tentative at this point, Kuang and Kopparapu cautioned.

"This is one of the conjectures we didn't really put out strongly in our paper, but it is something we think is a very enticing mechanism for us to pursue," Kuang said. The reason the researchers held back with this idea is that they have robust data for only one supercontinent — Pangaea — and not the ones that came before, he said.

"There seems to be some eye-sight correlation between oxygen and magnetic field and all the other supercontinents," Kopparapu said. "However, we don't have reliable data for oxygen [going farther back] than 540 million years, and so we are unable to make that kind of a conclusion for [farther back in time] and past supercontinents."

The researchers are already working on the next step, which is to search for other geophysical and geochemical factors that might link to the geomagnetic field and oxygen levels. For this, the authors say communication and collaboration between scientists is of paramount importance.

"One single mind cannot comprehend the whole system of the Earth," Kopparapu said. "We're like kids playing with Legos, with each of us having a separate Lego piece. We're trying to fit all of it together and see what's the big picture."

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

Scientists have captured magnetic signatures from Earth's ocean tides in the finest detail yet.

These faint signals, which certain satellites can detect when flying at very low orbits, may hold clues about magma distribution beneath the seabed, according to a statement from the European Space Agency (ESA).

As seawater ripples over our planet's magnetic field, it generates weak electric currents that in turn produce magnetic signals detectable from space. In a new study, published Dec. 2, 2024 in the journal Philosophical Transactions of the Royal Society A, researchers deciphered these signals using data from ESA's ongoing Swarm mission, which comprises three satellites that measure Earth's magnetic field.

"These are among the smallest signals detected by the Swarm mission so far," study lead author Alexander Grayver, a geophysist and senior lecturer at the University of Cologne in Germany, said in the statement.

Earth's magnetic field results from a swirling sea of electrically charged molten iron in the planet's outer core. Heat currents and Earth's spin both fuel the movement of this liquid iron. The core's movement creates a giant, bipolar envelope that extends into space, shielding us from cosmic radiation and charged particles emitted by the sun.

Related: Listen to haunting sounds of Earth's magnetic field flipping 41,000 years ago in eerie new animation

Swarm launched in 2013 and has been collecting information about Earth's magnetic field ever since. But clear signals created by ocean tides are difficult to obtain, because they are so faint they hardly ever break through the widespread "noise" in space, according to the statement.

In the late 2010s, several factors aligned that enabled Swarm to record the magnetic signatures of ocean tides in unprecedented detail. One of these factors was a dramatic reduction in the sun's activity, and another was the closeness of Swarm satellites to Earth.

"The data are particularly good because they were gathered during a period of solar minimum, when there was less noise due to space weather," Grayver said.

The sun follows a roughly 11-year cycle that dictates the level of activity at its surface. At the solar maximum, the sun emits huge waves of electromagnetic radiation and charged particles that obscure measurements of magnetic signals from Earth. Activity dies down during the solar minimum, making it easier for satellites to pick up these signals.

ESA initially planned to end the Swarm mission in 2017, but its valuable results prompted the agency to extend it. Over the years, drag has pulled the satellites closer to Earth, enabling the instruments on board to pick up faint signals that they could not have detected in their original, higher orbits.

"This is one of the benefits of flying missions for longer than originally planned, Anja Strømme, ESA's Swarm mission manager, said in the statement. "You can tackle scientific questions that weren't originally envisaged."

The new study shows that satellites can peer through the depths of Earth's oceans and extract useful information, Strømme said.

Swarm could stay operational until 2030, when the next solar minimum is due. Scientists hope that this will provide another rare opportunity to detect hidden ocean signals.

A bizarre dent in Earth's magnetic field above the southern Atlantic Ocean weakens the southern lights, new research finds. 

The South Atlantic Anomaly is a large, oval-shaped region over South America and the southern Atlantic Ocean where Earth's magnetic field is weakest. The anomaly is already well known for allowing charged particles from the sun to dip close to Earth's surface, exposing satellites orbiting above to high levels of ionizing radiation, according to NASA. 

Now, a study published Feb. 8 in the journal Geophysical Research Letters finds that this weak region also affects the southern aurora, the glowing lights in the upper atmosphere that can be seen at high latitudes. The southern lights occur over and around Antarctica and are the equivalent of the northern lights that dance over the Arctic and Subarctic. 

Auroras are caused by solar particles interacting with gas molecules in Earth's atmosphere and are usually considered largely under the control of the sun, said Zhi-Yang Liu, first author of the study and a researcher at the Institute of Space Physics and Applied Technology at Peking University in China. But the new research highlights the two-way nature of the relationship, Liu told Live Science in an email. 

Related: Mystery blobs in Earth's mantle may be linked to ancient gold and platinum that arrived from space

"Our discovery highlights the significance of Earth-related factors, such as anomalies in Earth's intrinsic magnetic fields that rotate with the Earth," Liu said. 

The researchers used data from an instrument aboard the FengYun-3E satellite, launched in 2021, that measures magnetic-field variations. They found a "substantial weakening" of magnetic fluctuations in the aurora australis, or southern lights, where it overlaps with the South Atlantic Anomaly. 

To confirm the findings, they also analyzed ultraviolet light from this region of the aurora using data from the U.S. Defense Meteorological Satellite Program. This also showed a weakening in the southern lights in the area of the anomaly. 

It's likely that this weakening is even visible to the naked eye, Liu and study co-author Qui-Gang Zong, also of the Institute of Space Physics and Applied Technology, noted. 

There are fewer auroras reported from China's Great Wall Station and other research stations on King George Island than in other Antarctic regions, they said. Research suggests that the ultraviolet and visible light in auroras behave similarly, Liu said, so it's likely that the visible light of the aurora is weakened by the South Atlantic Anomaly, too. 

The weakened magnetic fluctuations of the anomaly seem to reduce the amount of energy that can be put into the atmosphere by solar particles, Liu said, but the physics of the weakened aurora is not entirely understood. 

There may be feedback effects between the atmosphere and the solar energy that further complicate the picture. Future research will also investigate whether a similar phenomenon occurs on other planets, he said. 

An explosion of extremely rare pink auroras recently lit up the night sky above Norway after a solar storm slammed into Earth and ripped a hole in the planet's magnetic field. The breach enabled highly energetic solar particles to penetrate deeper into the atmosphere than normal, triggering the unusual colored lights.

The stunning light show was spotted Nov. 3 by a tour group led by Markus Varik, a northern lights tour guide from the Greenlander tour company based near Tromsø in Norway. The vibrant auroras emerged at around 6 p.m. local time and lasted for around 2 minutes, Varik told Live Science in an email.

"These were the strongest pink auroras I have seen in more than a decade of leading tours," Varik said. "It was a humbling experience."

The pink auroras emerged shortly after a small crack appeared in the magnetosphere — an invisible magnetic field surrounding Earth that is generated by the planet's fluid metal core. Scientists detected the breach after a minor G-1 class solar storm slammed into Earth on Nov. 3, according to Spaceweather.com.  

Related: Do extraterrestrial auroras occur on other planets? 

Auroras are formed when streams of highly energetic charged particles, known as solar wind, pass around the magnetosphere. The planet's magnetic field protects us from cosmic radiation, but the shield is naturally weaker at the North and South Poles, which enables the solar wind to skim through the atmosphere — usually between 62 and 186 miles (100 and 300 kilometers) above Earth's surface. As solar particles pass through the atmosphere, they superheat gases, which then vibrantly glow in the night sky, according to NASA.

Auroras most commonly appear green,  because oxygen atoms, which are abundant in the part of the atmosphere that solar wind normally reaches, emit that hue when they are excited. However, during the recent solar storm, the crack in Earth's magnetosphere enabled the solar wind to penetrate below 62 miles, where nitrogen is the most abundant gas, according to Spaceweather.com. As a result, the auroras gave off a neon pink glow as the supercharged particles smashed mostly into nitrogen atoms. 

The crack in Earth's magnetosphere also helped to generate strong green auroras throughout the night, Varik said.

The magnetosphere hole closed around 6 hours after it first opened. During this time, a strange ribbon of blue light also emerged in the skies above Sweden, where it hung motionless in the sky for around 30 minutes, according to Spaceweather.com.

However, experts are unsure if this unusual phenomenon was some never-before-seen type of aurora caused by the compromised magnetosphere, or if it was the result of something else. One expert suggested that the ribbon could have been made up of frozen fuel from a Russian rocket, but no rockets were spotted in the area, according to Spaceweather.com.

Earth has a new age: the Chibanian geologic time interval, which took place from 770,000 to 126,000 years ago, thanks to a layer of sediment found on a riverside cliff in southern Japan.

The Chibanian age was named after Chiba, the Japanese prefecture where the sediment was found, and was recently ratified by the International Union of Geological Sciences. That period is important because it included the most recent reversal of Earth's magnetic field, an article in Eos said. At various points in our planet's history, Earth's magnetic north and south poles have swapped locations. When that flip happens, it leaves a mark in rocks around the planet. The cliffside sediment in Chiba, Japan, may offer a richer record of that reversal than any other site on Earth.

Related: 50 interesting facts about Earth

That polar flip, known as the Brunhes-Matuyama reversal, is still the subject of some debate. A 2014 paper published in the Geophysical Journal International used information from a layer of sediment found in Italy to argue that the flip took place in the span of a few decades. A 2019 paper published in the journal Science Advances argued, relying on information from ancient lava flows in Hawaii, that the reversal took closer to 22,000 years. As an excellent geologic record of this flip, the Chiba sediment could eventually help resolve the debate.

Studying how the polarity reversal happened might help us understand what's going on today. Our planet's magnetic poles have wandered in recent years, and scientists don't fully understand why.

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Originally published on Live Science.

AUSTIN, Texas — Migrating animals that live in Earth's oceans may have a closer relationship with the sun than we thought. New research shows that healthy gray whales are nearly five times more likely to strand when there is a high prevalence of sunspots, and therefore high levels of radio waves emitted from solar storms. The researchers presented their findings here at the Society for Integrative and Comparative Biology meeting on Tuesday (Jan. 7). 

"It's a fascinating finding," Kenneth Lohmann, a biologist who studies magnetoreception (or how animals detect Earth's magnetic field) at the University of North Carolina at Chapel Hill, told Live Science in an email. "There have been several previous reports linking magnetic storms to whale strandings, but this is a particularly well-done and convincing analysis," said Lohmann, who was not involved in the study.

Scientists are unsure if whales use magnetoreception to navigate, but migratory whales, such as gray whales, are likely candidates because the ocean provides few other navigational cues, said study lead author Jesse Granger, a conservation biophysicist at Duke University in North Carolina. 

Related: Whale Album: Giants of the Deep

From March to June, gray whales swim north from the coast of Baja California, Mexico, to the cool, food-rich waters of the Bering and Chukchi seas, north of Alaska. Whales make their return trip south beginning in November. Occasionally, a seemingly healthy gray whale strands while en route. Although there are myriad reasons why a whale might strand, one possibility is that the whale made a navigational error when something was disrupting Earth's magnetic field or the whale's ability to detect it — like a solar storm, for example. 

Granger and her colleagues reviewed gray whale stranding data from the U.S. West Coast between 1985 and 2018 and found that live and otherwise healthy gray whales were stranding far more often when there were a high number of sunspots. 

But that finding alone doesn't explain how a sunspot could possibly cause a gray whale to get lost. Although sunspots cause a large increase in electromagnetic radiation, most of that radiation doesn't make it to our planet’s surface, because that light is blocked or scattered by Earth's atmosphere.

"However, there's a huge chunk in the radio frequency (RF) wave range that does make it all the way to the Earth," Granger said. "And, it's been shown in several species that RF noise can disrupt a magnetic orientation ability." 

The researchers found there was a 4.3-fold increase in the likelihood that a whale would strand on days when there was high RF noise (because of solar storms) compared with low RF noise. This suggests that the whale's magnetic receptor, or ability to read its map of the area, could be what's causing the whale to take a detour — not that the map is incorrect, Granger said. 

But scientists still don't know for sure if whales even have a magnetoreceptive sense or not. All we know, Granger said, is that "whales are stranding a lot more often when the sun is doing crazy stuff." 

Magnetic storms are also known to cause other issues for animals unrelated to navigation, Lohmann said. "So, more work will be needed to determine whether the storms are affecting whale navigation or having some other effect."

One of the team's next steps, Granger said, is to see if this is a phenomenon that's seen in other migratory species and in other parts of the world where the magnetic field may not be as easily detected. 

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Correction note: This article was updated on Jan. 17, 2020 to correct the 4.8-fold increase in strandings to a 4.3-fold increase. We apologize for the error.   

Originally published on Live Science.

For some creatures, the magnetic field that hugs our planet serves as a compass for navigation or orientation.

Migratory birds, sea turtles and certain types of bacteria are counted among the species with this built-in navigation system. But what about humans? According to a new study, humans can also sense Earth's magnetic field.

The new study, published today (March 18) in the journal eNeuro, provides the first direct evidence, from brain scans, that humans can do so, likely through magnetic particles scattered around the brain.

The ability to detect the magnetic field, called magnetoreception, was first suggested to exist in humans back in the 1980s. But subsequent studies of the brain, from the 1990s, didn't find evidence of the ability. [Top 10 Mysteries of the Mind]

But with access to new data analysis techniques, an international group of researchers decided to take another look.

Manipulating the magnetic field

To study whether humans can sense the magnetic field, 34 adults were asked to sit in a dark test chamber adorned with large, square coils. Electric currents traveled through these coils, changing the magnetic field in the chamber..

The intensity of this magnetic field was about the same as the one that surrounds our planet, said lead study author Connie Wang, a doctoral student at the California Institute of Technology. For comparison, it's about 100,000 times weaker than the ones created by MRI machines, Wang noted.

The participants were told to relax and close their eyes while the researchers manipulated the magnetic field around them. During the experiment, electroencephalogram (EEG) machines measured a type of brainwave called an alpha wave. Alpha waves are known to decrease in amplitude when the brain picks up a signal, whether it be sight, sound … or something magnetic.

The brain responds

Of the 34 participants, brain scans from four individuals showed strong reactions to one change in the magnetic field: a shift from northeast to northwest. This shift would be the same as a person outside the chamber shifting their head quickly from left to right, except the head moves through the static magnetic field rather than the field moving around it. [Earth Quiz: Do You Really Know Your Planet?]

In the four individuals, alpha brain waves decreased in amplitude by as much as 60 percent. But they responded only when the field shifted from northeast to northwest — not in the other direction.

"We weren't really expecting an asymmetrical response," Wang told Live Science. Though it’s unclear why this happened, the researchers think it could be something unique to individuals, just like how some people are right-handed and some left-handed.

Several participants also had a strong response to another set of experiments that shifted the incline of the field, which is what would happen if you traveled between the Northern and Southern hemispheres.

To ensure the results weren't a fluke, the study responders were re-tested several weeks later — and the results held true. Stuart Gilder, a professor of geophysics at the Ludwig-Maximilian University of Munich who was not part of the new study, said that the repeated findings made the study convincing.

Gilder said that he didn't view the finding that most people couldn't sense the magnetic field as a count against the study, because the ability could be expressed differently in different brains. "Some people are really good at art and some people are really good at math," Gilder told Live Science. Organs don't "have to behave or react in the same way."

Still, the study does raise some additional questions, he noted. For example, how would people perceive the field if they had been lying down, or the magnetic field had been moving slower?

Ancient navigation

It's unclear why some humans seem to be capable of magnetoreception, but in theory, the skill could help with orientation, or be a remnant of an ability that evolved early on to help creatures — even ancient hunter-gatherers — navigate. "Many animals use the Earth's magnetic field for navigation," Wang told Live Science. "There's such a wide range of creatures that have this sense that we think humans, at least, have some remnants of this sense, even if we don't use it so much in our daily lives anymore."

And many questions remain about magnetoreception in general, like how it works. Indeed, scientists have figured out how magnetoreception works in just one type of creature: a type of bacteria called magnetotactic bacteria. These microbes migrate along the field lines of our planet's magnetic field using magnetic particles called magnetite (Fe3O4).

These magnetite particles have been known to exist in the human brain for decades — and were first found by Joseph Kirschvink, a professor of geobiology at Caltech, who is the senior author of the new study.

What’s more, a study published in August 2018 in the journal Scientific Reports from Gilder's group found that these magnetic particles were scattered throughout the human brain. Their widespread presence in the brain suggested that the particles likely served some kind of biological purpose, the authors of that study concluded.

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Editor's Note: This article was updated on March 19 to clarify that magnetic particles aren't confined to a "brain" in microbes. Bacteria are typically made up of single cells and so they do not have brains.

Originally published on Live Science.

A gradual weakening in Earth's geomagnetic field has raised concerns that the field could flip, reversing magnetic north and south. But now, new research suggests the field has been in a similar state before — without making a move.

In a study published in the journal Proceedings of the National Academy of Sciences today (April 30), researchers compared the current magnetic field, which is created by the churning of Earth's core, with the magnetic field of eons past. They found that today's patterns don't resemble the two most extreme disruptions in the past 50,000 years, when the magnetic field nearly reversed. [7 Ways the Earth Changes in the Blink of an Eye]

Instead, the modern field appears similar to the field during two other periods — one 49,000 ago, and one 46,000 years ago — when the field wobbled but didn't flip-flop.

Even a wobble, though, could have ramifications, the authors wrote. If the field continues to weaken, it could affect things like electronics aboard low-Earth-orbit satellites, even without a total reversal of magnetic north and south.

Protective feature

Earth's geomagnetic field shields the planet's surface from damaging charged particles in space, so it's important for both life on Earth and the electric grid. "Solar storms" that barrage Earth with higher-than-usual levels of charged particles can cause problems with satellite communications and even the electrical grid, as happened in 2003, when "Halloween storms" forced the rerouting of aircraft and took out power in parts of Sweden for an hour.

Currently, magnetic north is very close to the North Pole, while magnetic south is near the South Pole. That's been the case for about 780,000 years — the last time the geomagnetic field underwent a complete reversal, with magnetic north and south swapping places. But the field has been weakening by about 5 percent per century since direct observations started in 1840, and indirect observations hint that this weakening might have been going on for at least 2,000 years, Maxwell Brown, who studies paleomagnetism at the University of Iceland, and his colleagues wrote in their new paper. A particularly weak area called the South Atlantic Anomaly, which stretches from South Africa to Chile, has been pinpointed as a potential ground zero for a global polarity reversal.

Brown and his colleagues wanted to compare today's conditions with the magnetic field of years past. They focused on two "excursions," which are major disruptions of the geomagnetic field that don't necessarily involve a global reversal of magnetic north and south. One, the Laschamp excursion, occurred about 41,000 years ago. During that excursion, the magnetic field was a complex muddle without a clear magnetic north and south. The other, the Mono Lake excursion, happened about 34,000 years ago and was marked by a very weak magnetic north and south.

Natural variation

The researchers modeled these geomagnetic hiccups and found that neither looked much like the field's conditions today. During the Laschamp excursion, magnetic north and south weakened with increasing rapidity, and two large anomalies grew over Central America and Southeast Asia almost simultaneously. Over thousands of years, patches where the direction of magnetism was reversed popped up, and the intensity of the magnetic field dropped very low.

During the Mono Lake excursion, magnetic north and south weakened but for a shorter period of time, and lots of little patches of reverse magnetism appeared across the globe. There were also lots of patches of altered intensity in the field's strength, which appeared erratically and vanished again. Over a couple thousand years, the field stopped wavering and stabilized again with a strong north and south.

Today's field isn't as weak as the field was during the Laschamp or Mono Lake excursions, and it has just the one intensity anomaly, the South Atlantic Anomaly. So, Brown and his co-authors argue that this isn't enough to seed a full global flip-flop. Rather, they wrote, a major excursion or magnetic field reversal probably requires a lot of little nucleus points around the globe. Backing up their argument, they found two times — 49,000 years ago and 46,000 years ago — when the geomagnetic field looked a lot like today's. In both cases, the field recovered without any extreme events resulting.

If the researchers are right and the magnetic field doesn't reverse, there could still be headaches in store for humans. Already, the South Atlantic Anomaly has occasionally caused electrical failures on satellites, Brown and his colleagues wrote.

"[W]ith a continued decrease in field intensity," they continued, "issues such as this will become more widespread."

Original article on Live Science. 

Why do otherwise healthy sea creatures end up stranded along coastal areas around the world? NASA scientists are searching for the answer.

Whales, dolphins and porpoises — known collectively as cetaceans — partially use magnetic-field sensing to navigate. According to NASA scientists, one explanation for these mysterious strandings could be that the animals' internal compasses become confused during severe solar storms, which affect Earth’s magnetic fields, and so they lose their way. To investigate this marine mystery, NASA has launched a study that will determine whether there is a link between solar storms and animal beachings.

Cetaceans become stranded around the world in groups as small as three or as large as several hundred per event. According to Katie Moore, a collaborator on the NASA study and director of the International Fund for Animal Welfare's Animal Rescue Program, the global phenomenon occurs most often in New Zealand, Australia and Cape Cod, Massachusetts. [Images: Sharks & Whales from Above]

Despite the prevalence of such beaching events, study leader Antti Pulkkinen, a heliophysicist (a person who studies the effects of the sun on the solar system) at NASA's Goddard Space Flight Center, said there has been very little quantitative research.

"We estimate that records on the order of hundreds of cetacean mass strandings will be available for study, thus making our analyses statistically significant," Pulkkinen said in a statement. "What we’re going to do is throw cold, hard data at this. It's a long-standing mystery and it’s important that we figure out what’s going on."

Pulkkinen and his collaborators will work with the federal Bureau of Ocean Energy Management and the International Fund for Animal Welfare to sift through cetacean mass stranding reports, space-weather databases and field observations. The researchers expect to complete the study by the end of September.

The scientists said the results won't necessarily imply a link, but the study will be the first thorough research into whether a correlation exists between the solar storms and beaching events.

"If we understand the relationship between the two, we may be able to use observations of solar storms as an early warning for potential strandings to occur," Moore said. "This would allow stranding responders in global hotspots, and, really, around the world, to be better prepared to respond, thus having the opportunity to save more animals."

Original article on Live Science.

The fiery demise of ancient huts in southern Africa 1,000 years ago left clues to understanding a bizarre weak spot in the Earth's magnetic field — and the role it plays in the magnetic poles' periodic reversals.

Patches of ground where huts were burned down in southern Africa contain a key mineral that recorded the magnetic field at the time of each ritual burning. Those mineral records teach researchers more about a weird, weak patch of Earth's magnetic field called the South Atlantic Anomaly and point the way toward a possible mechanism for sudden reversals of the field.

"It has long been thought reversals start at random locations, but our study suggests this may not be the case," John Tarduno, a geophysicist from the University of Rochester in New York and lead author of the paper, said in a statement. [How Earth's Magnetic Field Shielded Us from 2014 Solar Storm]

Tarduno told Space.com in an interview that data from the huts suggest that the strange weak patch "forms, and it decays away, and it forms, and it decays away; eventually, one might form and get really large, and then we might actually have a geomagnetic reversal."

Something strange in the South Atlantic

The South Atlantic Anomaly is a dent in Earth's shield against cosmic radiation, 124 miles above the ground (200 kilometers). It may be the most dangerous place in the Earth's sphere for satellites and spacecraft to traverse, because anything electronic traveling through it is vulnerable to strong radiation from space and tends to malfunction.

Even the Hubble Space Telescope takes no measurements when passing over  the anomaly. It's an area where, instead of pointing outward, part of the Earth's magnetic field actually ushers energetic particles down instead of repelling them, weakening the overall field in the area. And it has been growing.

"Some have postulated that the Earth's magnetic field is leaking out the wrong way at that particular spot," Rory Cottrell, a geologist also at the University of Rochester and co-author of the new paper, told Space.com. "One theory is that changes in the South Atlantic Anomaly could be responsible for the decrease in the overall magnetic field that we're seeing, because these patches are growing or changing over time."

Many researchers have speculated that this kind of anomaly is temporary, caused by changes of flow within the Earth's outer, iron core, which generates the planet's magnetic field. Such anomalies, in weakening the magnetic field, may bring the Earth closer to a magnetic reversal — when the magnetic north and south poles on Earth switch places, rearranging the magnetic field over the course of 1,000 to 10,000 years (although it can happen faster). The process generally happens every 200,000 to 300,000 years, after the magnetic field weakens enough, but the last magnetic-field reversal occurred 780,000 years ago.

The new data from the African burnings suggests that the South Atlantic Anomaly was up to its same field-weakening tricks over 1,000 years ago; if it's caused by something permanent near the Earth's core, it might play an important role in the Earth's magnetic-pole reversals.

Burn it all down

Modern magnetic records only stretch back for the past 150 years or so, and within that time frame, researchers have seen the Earth's magnetic field rapidly decrease in intensity. But the researchers used the Iron Age remnants of African villages to extend their view even further back, from A.D. 1,000 to A.D. 1,850 — and the record reveals that the South Atlantic Anomaly was going strong at that time, too. [Earth Quiz: Do You Really Know Your Planet?]

Throughout that time, the inhabitants of ancient African villages would burn down the huts and grain bins in their villages on a regular basis, giving scientists key, consistent data throughout that time period.

"They had this ritualistic burning of villages," Tarduno told Space.com. "Particularly in times of drought, the conclusion would be that there might have been some offence in the village, so the solution was to have a burning down of the village." The process was intended to cleanse the village, their collaborator archaeologist Thomas Huffman, from Witwatersrand University in South Africa, said in the statement.

At the very least, it cleansed the ground: The burning villages would reach temperatures of over 1,800 degrees Fahrenheit (1,000 degrees Celsius), which would melt the magnetic compounds like magnetite in the clay floors. The magnetite would become remagnetized by the Earth's magnetic field at the precise instant it cooled, ready to be analyzed centuries later.

"The hut floors are actually very good magnetic recorders," Tarduno said. "Sort of like minimagnetic observatories back in time."

Researchers had obtained very little historical data in the southern hemisphere, and none in southern Africa before these findings. The new baked-clay records revealed an eerily familiar picture of the Earth's magnetic field: Just like today, the Earth's magnetic field at the time was steadily weakening, with a focus on that same South Atlantic Anomaly. The effect did not appear to be continuous, but rather seemed to be a recurring event in that part of the globe, whose weakening power comes and goes over time.

Digging deeper

To Tarduno's group, that consistently recurring spot of weakening suggests that a permanent feature deep below the Earth's surface may be generating the South Atlantic Anomaly and might therefore play a role in the reversal of the Earth's magnetic field.

That feature is a section of particularly hot and dense mantle rock just above the Earth's outer core. The section is 1,860 miles (3,000 km) below southern Africa and the Atlantic, and it's about as wide as the distance between New York and Paris. Scientists call it the Large Low Shear Velocity Province, and Tarduno's group suspects that its sharp boundaries might disrupt the flow of iron within the Earth's core, creating a strange, field-weakening eddy that could lead to reversals time and time again.

The researchers' model is only one of many theories about magnetic pole reversal, and they're focusing on refining the mathematics and gathering more, even earlier data from southern Africa to further track the weak spot.

"No one knows what causes reversals, and there is no agreement on whether we can ever even find convincing evidence to forecast a reversal," Ron Merrill, a geophysicist from the University of Washington, who was not involved in the study, told Space.com in an email.

While the new magnetic field records in Africa are useful in their own right, he wrote, it will take much more testing and theory to make a solid connection between the feature near the Earth's core and the magnetic field's weakening and reversal (and the long-lasting nature of the South Atlantic Anomaly).

The new research can't predict the next magnetic field reversal, but finding a connection between the ancient irregularity near the Earth's core and a weakening magnetic field would be one more step toward deciphering the incredibly complex magnetic system that protects humanity from the harsh radiation of space.

This research is detailed in the July 28 edition of the journal Nature Communications.

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com

A key ingredient of the early Earth may have been a chunk of rock much like Mercury, scientists say.

This finding could help explain how Earth's magnetic field has lasted for billions of years, researchers added.

Scientists think Earth formed at about the same time as the sun and the rest of the solar system about 4.6 billion years ago from a giant, rotating cloud of gas and dust. Earth and the other rocky planets coalesced from smaller asteroid-sized bodies that accreted or stuck together to form ever-larger chunks of rock. [Earth Quiz: Do You Know Your Planet?]

The meteorites that crash into Earth are usually thought to represent the building blocks that the planet grew from. However, Earth's crust and mantle puzzlingly have a higher proportion of the element samarium to the element neodymium than seen in most meteorites.

New experiments now suggest that the addition of a sulfur-rich Mercury-like body to the early Earth could explain this anomaly. This research could also help solve another mystery — how the Earth's magnetic field has lasted for billions of years.

"A Mercury-like body added to Earth during accretion would solve two important problems — that is, kill two birds with one stone," study co-author Bernard Wood, a geochemist at the University of Oxford in England, told Space.com.

Cooking up the Earth's core

The researchers performed experiments with samples of material under conditions mimicking those at which Earth formed — temperatures between 2,550 and 3,000 degrees Fahrenheit (1,400 and 1,640 degrees Celsius) and pressures of 1.5 gigapascals. For comparison, 1 gigapascal is nearly 10 times greater than the pressure at the bottom of the Mariana Trench, the deepest part of the ocean.

The samples of material the scientists tested contained traces of elements such as samarium, neodymium, and uranium. These elements are normally chemically attracted to silicate rock, which makes up most of the Earth's crust and mantle. They do not usually dissolve in iron sulfide, which makes up a significant fraction of Earth's outer core.

The scientists found that if the early Earth incorporated a rocky body like Mercury, which is high in sulfur, this could make samarium and neodymium dissolve better in iron sulfide. This in turn would make samarium and neodymium more likely to sink down toward Earth's core.

However, samarium is more attracted to silicate rock than neodymium is. This would have made samarium a bit less likely to sink downward, which could explain why there is a greater proportion of samarium to neodymium in Earth's crust and mantle. 

You live here, so we figure you ought to be well grounded in Earth facts. But you might find these questions a little tough and tricky. Good luck!

Earth Quiz: Do You Really Know Your Planet?

Magnetic field mystery

These experiments could also help solve a mystery concerning Earth's magnetic field.

Prior research suggests that Earth has possessed a magnetic field for at least 3.5 billion years. Earth's magnetic field results from churning metal in the planet's outer core, but it was uncertain how Earth's core could have remained molten for so long.

The new experiments revealed that if the early Earth engulfed a sulfur-rich Mercury-like body, uranium could have dissolved better in iron sulfide. This in turn would help uranium sink toward Earth's core. Uranium is a radioactive element that generates heat, which could have kept Earth's core molten.

Wood and study lead author Anke Wohlers at the University of Oxford detailed their findings in the April 15 edition of the journal Nature.

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Strange stripelike features in Earth's magnetic field are caused by the planet's spin, and not by the constant bombardment of solar particles as previously thought, scientists say.

The so-called "zebra stripes" form when the electric field around Earth generated by the planet's rotation — previously thought to be too weak to impact the fast-moving particles — creates a striped pattern in the inner electron belt.

"Features similar to zebra stripes were previously inferred from low-altitude electron measurements," said lead study author Sasha Ukhorskiy of Johns Hopkins University in Maryland. Ukhorskiy was the lead author of the new study that examined the patterns of charged particles and modeled their interactions with Earth's rotation. [Earth Quiz: Do You Truly Know Your Home Planet?]

The "zebra stripes" were previously thought to be caused by the changing flow of particles streaming from the sun.

"It is because of the unprecedented high energy and temporal resolution of our energetic particle experiment RBSPICE — part of the Van Allen Probes NASA mission — that we now understand that the inner belt electrons are, in fact, always organized in zebra patterns," Ukhorskiy told Space.com via email.

A striped shield

Earth's magnetic field surrounds the planet like a shield, protecting it from the constant bombardment of charged particles from the sun. A slight tilt in the axis of this field creates a weak electric field that permeates the inner radiation belt. The interaction between the two creates the zebra stripes, which are concentrated distributions of highly energetic electrons trapped in Earth's magnetic field. These features are invisible to the human eye.

"If the inner belt electron populations are viewed as a viscous fluid — which is just an analogy — these global oscillations stretch and fold that field, much like taffy is stretched and folded in a candy-store machine," Ukhorskiy said. "This stretching-and-folding process results in the striped pattern across the entire inner electron belt."

Before this new finding, scientists had thought the field created by the planet's rotation was too weak to form the zebra stripes because it only changed the speed of the particles by 1 to 2 kilometers per second (0.6 to 1.2 miles per second) — which isn't much, considering the particles had been traveling at almost 100,000 km/s. Instead, the scientists attributed the formation of the features to interactions with the ever-changing solar wind and the presence of geomagnetic storms.

Working with a team of scientists, Ukhorskiy studied the data gathered by the Van Allen Probes to determine that the zebra stripes are a constant fixture in Earth's magnetic field, rather than features whose formation are dictated by the ever-changing presence of the solar wind.

"The fact that zebra patterns are observed — and are more clear — during intervals of quiet solar-wind conditions was the main indication that it must be the Earth's rotation that drives them," Ukhorskiy said.

The presence of the stripes only during calm periods was the first clue that the solar wind was not the driving force behind them. Ukhorskiy and his team went on to model the interactions between the magnetic field and the weak electric field generated by the planet's rotation. They concluded that this interaction created the zebra stripes.

Zebra stripes only form in the inner electron belt, which extends from Earth's atmosphere up to approximately 8,000 miles (13,000 kilometers) above the planet's surface. The outer electron belts take the brunt of the solar wind, making an unstable environment of competing processes.

The new findings were published online March 19 in the journal Nature.

Stripes in the solar system

Launched in 2012, the Van Allen Probes consist of two spacecraft located in the concentrated regions of Earth's electric field known as the Van Allen belts. The satellites study electrons in the radiation belt, and how their behavior changes over time and as a result of interactions with solar particles.

Although the radiation belt deflects most of the harmful material streaming from the sun, massive solar storms on the star occasionally hurl large quantities of material toward the planet that can affect satellites, communication systems and power grids. Understanding how Earth's shield interacts with these particles can help scientists gauge the measures needed to protect these systems.

Zebra stripes may surround other planets in the solar system. Ukhorskiy said the rotational forces of Jupiter and Saturn are far more prominent in affecting their plasma environments, making the concentrated pattern a likely feature in their radiation belts. Launched in 2011, NASA's Juno mission is set to reach Jupiter in July 2016, and should spot any zebra stripes in the gas giant's radiation belt.

When asked about the next step, Ukhorskiy said, "In my opinion, the most intriguing science question is whether similar or more prominent features exist at the outer planets."

Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

Earth may have possessed a magnetic field shortly after its birth, suggesting that magnetic shielding could have played a larger role in the development of life on Earth than currently thought, researchers say in a new study.

Nowadays, churning that occurs in Earth's liquid outer core creates the dynamo that generates Earth's magnetic field. This churning, known as convection, happens because of heat flow — electrically conductive molten iron alloy in the core's outer layer gets hot and rises, then dissipates this heat and sinks.

Investigations of ancient rocks suggest Earth has possessed a magnetic field for at least the past 3.5 billion years of its 4.6-billion-year history. Earth's magnetic field leaves an imprint on magnetically sensitive minerals in cooling lava, literally setting in stone the direction the planet's magnetic poles were aimed when the rocks formed.

However, recent experiments hint Earth's core might not have been able to generate a magnetic field until about 2.1 billion years ago. These studies suggested the amount of heat flowing out of the core needs to be nearly three times greater than once thought to create enough convection to generate a dynamo. The core could not sustain this huge amount of heat flow for the entire 3.5-billion-year history of Earth's magnetic field.

In the new study, researchers suggest Earth's first magnetic field may not have originated from the planet's core as it does today, but from a giant ocean of magma sitting on top of the core.

Moreover, this magma ocean may have given Earth a magnetic field beginning 4.5 billion years ago, some 1 billion years earlier than Earth is currently suspected to have possessed a magnetic field.

"If the model is correct, it shatters nearly every assumption about the early Earth," study author Dave Stegman, a geophysicist at the University of California, San Diego, told LiveScience's OurAmazingPlanet.

'Far-reaching consequences'

Past research suggested a magma ocean might have existed in the lowermost part of Earth's mantle layer between the core and crust from very early in Earth's history. This ocean would have existed from about 4.5 billion years ago to at least about 2.5 billion years ago. Oregon State University geophysicist and study co-author Leah Ziegler read about how a magma ocean within Jupiter's moon Io might influence Jupiter's magnetic field and wondered if Earth's ancient magma ocean could have generated a magnetic field.

Ziegler and Stegman modeled a range of electrical and magnetic properties that molten silicate rock in this magma ocean might have possessed. The researchers found that the molten rock's electrical conductivity might have been high enough to drive a dynamo early in Earth's history.

"The most important implication is that the Earth's early magnetic field was not generated in the core as has always been previously thought, but rather from inside the mantle," Stegman said.

If Earth had a magnetic field shortly after its birth, "this could have far-reaching implications," Stegman added. For example, if Earth had magnetic shielding from the sun that early on, this may have had consequences for the development of life on Earth.

"The first living cells on Earth may have first appeared 3.5 billion years ago, so perhaps the origin of life was related to the stable surface environment allowed by [the] protection of a magnetic field around Earth," Stegman said. "Magnetic shielding would also protect the atmosphere from being eroded away by the solar wind."

It remains uncertain if silicate liquids at the extreme pressures and temperatures found in this magma ocean would have been electrically conductive enough to drive a dynamo. The researchers plan to test their idea with a more sophisticated model of magnetic field generation.

"If our next results are also favorable, that should provide enough impetus for other disciplines to more seriously consider investigating this model," Stegman said.

Ziegler and Stegman detailed their findings online Nov. 26 in the journal Geochemistry, Geophysics, Geosystems.

Follow OurAmazingPlanet @OAPlanet, Facebook and Google+. Original article at LiveScience's OurAmazingPlanet.

The Earth's magnetic field controls the direction and speed at which Earth's inner and outer cores spin, even though they move in opposite directions, new research suggests.

Scientists have long suspected that Earth's magnetic field — which protects life from harmful space radiation — drifts in a slightly westerly direction. That theory was established in the 1690s, when geophysicist Edmund Halley (the same Halley who spotted the eponymous comet) sailed aboard a research vessel through the South Atlantic Ocean and collected enough compass readings to identify this shift.

By the mid-20th century, geologists had gathered further evidence for this drift and had determined that the westerly rotation of the magnetic field exerts a force on the liquid outer core— composed of a molten mix of iron and nickel — that causes it to rotate in a westerly direction. Decades later, geophysicists used deep seismic data to determine that the inner core — a solid iron-nickel alloy that is about the size of the moon — rotates in an easterly direction, at a greater speed than the rotation of the Earth itself.

But, until now, scientists have regarded these rotations within the two layers of the core as separate, with no relation to each other.   

Now, researchers at the University of Leeds in England have found a common link between the two rotations by creating a computer model that shows how the rotation of the Earth's magnetic field can both pull the liquid outer core in a westerly direction while also exerting an opposite force on the inner core that causes an easterly rotation.

"Previously, there have been these two independent observations, and there has not been a link between them," study co-author Philip Livermore, of the University of Leeds, told LiveScience's OurAmazingPlanet. "We argue that the magnetic field itself is pushing on the outer core, and there is an equal and opposite push on the inner core."

The Earth's magnetic field — created by the convection of hot liquid metal within the outer core — undergoes slight fluctuations roughly every decade. The inner core's rotation rate has also been shown to fluctuate on a similar timescale. These new results help explain why these two phenomena occur on the same timescale, since one has now been shown to affect the other, the researchers say.

The findings were detailed in the Sept. 16 issue of the journal Proceedings of the National Academy of Sciences.

Follow Laura Poppick on Twitter. Follow LiveScience on Twitter, Facebook and Google+. Original article on LiveScience's OurAmazingPlanet.

An extinct species of tool-making humans apparently occupied a vast area in China as early as 1.7 million years ago, researchers say.

The human lineage evolved in Africa, with now-extinct species of humans dispersing away from their origin continent more than a million years before modern humans did. Scientists would like to learn more about when and where humans went to better understand what drove human evolution.

Researchers investigated the Nihewan Basin, which lies in a mountainous region about 90 miles (150 kilometers) west of Beijing. It holds more than 60 sites from the Stone Age, with thousands of stone tools found there since 1972 — relatively simple types, such as stone flakes altogether known as the Oldowan. Researchers suspect these artifacts belonged to Homo erectus, "thought to be ancestral to Homo sapiens," Hong Ao, a paleomagnetist at the Chinese Academy of Sciences in Xi'an, told LiveScience. [Photos: New Human Ancestors from Kenya]

The exact age of these sites was long uncertain. To find out, Ao and his colleagues analyzed the earth above, below and in which stone tools at the Shangshazui site in the Nihewan Basin were found. The tools in question were stone blades potentially used for cutting or scraping.

The scientists analyzed the way in which the samples of earth were magnetized — since the Earth's magnetic field has regularly flipped numerous times over millions of years, looking at the manner in which the magnetic fields of minerals are oriented can shed light on how old they are. The researchers discovered this site in northern China might be about 1.6 million to 1.7 million years old, making it 600,000 or 700,000 years older than previously thought.

Horse, elephant and other fossils suggest the area back when the stone tools were made was mainly grassland interspersed with patches of woodland. A lake between the mountains there was probably a major attraction for hominid explorers, providing water and a range of other food sources, while the mountains could have represented an important material source for making stone tools. The researchers suggest hominid migrations to East Asia during the early Stone Age were a consequence of increasing cooling and aridity in Africa and Eurasia.

Given that slightly older artifacts and bones belonging to Homo erectus were previously discovered in southern China more than 1,500 miles (2,500 km) away, these new findings suggest early and now-extinct human species may potentially have occupied a huge territory in China.

"Homo erectus occupied a vast area in China by 1.7 million to 1.6 million years ago," Ao said.

The scientists detailed their findings online Aug. 15 in the journal Scientific Reports.

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Earth's internal engine is running about 1,000 degrees Celsius (about 1,800 degrees Fahrenheit) hotter than previously measured, providing a better explanation for how the planet generates a magnetic field, a new study has found.

A team of scientists has measured the melting point of iron at high precision in a laboratory, and then drew from that result to calculate the temperature at the boundary of Earth's inner and outer core — now estimated at  6,000 C (about 10,800 F). That's as hot as the surface of the sun.

The difference in temperature matters, because this explains how the Earth generates its magnetic field. The Earth has a solid inner core surrounded by a liquid outer core, which, in turn, has the solid, but flowing, mantle above it. There needs to be a 2,700-degree F (1,500 C) difference between the inner core and the mantle to spur "thermal movements" that — along with Earth's spin — create the magnetic field.

The previously measured core temperature didn't demonstrate enough of a differential, puzzling researchers for two decades. The new results are detailed in the April 26 issue of the journal Science.

The centerpiece of the experiment was a new X-ray technique that takes measurements faster than  before. Iron samples compressed in the laboratory typically last for only a few seconds, making it difficult to determine in previous experiments if the iron is still a solid, or if it is starting to melt.

The technique makes use of diffraction that occurs when X-rays, or other forms of light, hit an obstacle and bend around it. Scientists sent X-ray bursts at the sample and observed the "signature" of heating, which is a diffuse ring, that pinpointed the temperature.

These experiments pegged the melting point of iron at 4,800 C (about 8,700 F) at a pressure of 2.2 million times that is found on Earth's surface at sea level.

Extrapolating from that measurement, scientists estimated the boundary between Earth's inner and outer core is a searing 10,832 F, give or take about 930 degrees, at a pressure of 3.3 million atmospheres (or 3.3 million times the atmospheric pressure at sea level).

Participating organizations in the experiment include CEA (a French national technological research organization), the French National Center for Scientific Research (CNRS) and the European Synchrotron Radiation Facility (ESRF).

Follow Elizabeth Howell @howellspace, or OurAmazingPlanet @OAPlanet, Facebook and Google+. Original article at LiveScience's OurAmazingPlanet.

Glowing red arcs invisible to the naked eye have now been detected high above most of Europe using advanced cameras pointed at the sky.

When streams of high-energy, charged particles come rushing from the sun to batter Earth, they cause what are called geomagnetic storms. These events are disruptions in the magnetosphere, the part of Earth's atmosphere dominated by the planet's magnetic field. The most dramatic effects of these storms are giant, bright auroras in Earth's polar regions, but the tempests result in other striking consequences as well, such as faintly glowing red arcs high up in the ionosphere. This is the electrically charged part of Earth's atmosphere, stretching from about 50 to 370 miles (85 to 600 kilometers) above the Earth.

The arcs give off a very specific wavelength of red light, but are too faint to see with the naked eye. They appear at lower latitudes, unlike auroras, which typically occur over higher latitudes.

Scientists had thought there was too much light pollution over Europe for the dim, red arcs to be visible. But now, the new All-Sky Imaging Air-Glow Observatory (ASIAGO), located in northern Italy, is using cameras with highly sensitive sensors and a fish-eye lens to observe these red arcs and faint auroral activity over most of the continent. [Image Gallery: Amazing Auroras]

An international team of scientists watched the sky with the observatory during a geomagnetic storm that struck Earth in 2011. After comparing their observations with satellite- and ground-based observations, the researchers found that red arcs could reach all the way down to Europe, stretching from Ireland in the west to Belarus in the east.

The fact that scientists can now see these arcs over Europe means that, in combination with similar data from the Americas and the Pacific Ocean, researchers can now see how long the arcs stretch across vast distances over the planet "and thus how long it takes the magnetosphere to be drained of its storm-time energy," researcher Michael Mendillo, a space physicist at Boston University, told OurAmazingPlanet. (Red arcs happen when oxygen atoms in the ionosphere emit light, after being excited by electrons heated at greater heights in Earth's magnetosphere.)

Such data could in turn help scientists analyze the effects of space activity on radio communications in real time and support projects aiming to model space weather, researchers added.

The scientists detailed their findings online Feb. 25 in the journal Space Weather.

Follow OurAmazingPlanet @OAPlanet, Facebook & Google+. Original article at LiveScience's OurAmazingPlanet.

Cooking stones from New Zealand could reveal the magnetic history of the Earth going back hundreds of years, new research suggests.

The stones were used by the Maoris, native New Zealanders, in their cooking ovens, called hangis over the past several hundred years. The stones got so hot that the minerals in them with magnetic properties would have aligned with the Earth's magnetic field at the time.

BBC News reported the findings, which were presented Friday (Dec. 7) at the annual meeting of the American Geophysical Union in San Francisco.

"We have very good palaeomagnetic data from across the world recording field strength and direction — especially in the Northern Hemisphere," one of the study authors, Gillian Turner from Victoria University, in New Zealand, told BBC News. "The southwest Pacific is the gap, and in order to complete global models, we're rather desperate for good, high-resolved data from our part of the world."

Earth's magnetic field changes over time, because molten iron in the planet's outer core sloshes around.

Turner is trying to create a record of the Earth's magnetic history over the last 10,000 years. To reconstruct the planet's historic magnetic field, geologists normally look at pottery shards, which contain minerals that demagnetize at high temperatures and then realign with the Earth's magnetic field as they cool. The stronger the field, the more magnetic the minerals, Turner told BBC News.

But the Maoris who first settled in New Zealand around 700 or 800 years ago didn't use pottery. So instead, she decided to look at Maori hangis, which the native islanders have historically used to steam their food.

Legend has it the hangis get white hot, which would mean they reached up to about 2,000 degrees Fahrenheit (1,100 degrees Celsius) – well above the Curie temperature at which minerals demagnetize.

The team experimented with modern-day hangis, heating them and then placing a compass atop them to see how the magnetic field realigned once they cooled. They found the ovens did get hot enough to record the magnetic field.

Now, the researchers are looking for archaeological digs throughout New Zealand that contain traces of old cooking stones.

By testing their magnetic field alignment and using radioactive carbon to date the stones, the team hopes to reconstruct nearly a millennia of the Earth's historical magnetic field in the Southern Hemipshere, where data is more sparse.

To go further back in time, the team will look at other rock sources, such as volcanic rocks from eruptions and lake sediments.

Follow LiveScience on Twitter @livescience. We're also on Facebook & Google+. 

Our planet's protective magnetic bubble may not be as protective as scientists had thought. Small breaks in Earth's magnetic field almost continuously let in the solar wind — the stream of magnetic, energized plasma launched by the sun toward the planets — new research has found.

"The solar wind can enter the magnetosphere at different locations and under different magnetic field conditions that we hadn't known about before," Melvyn Goldstein, an astrophysicist at NASA's Goddard Space Flight Center, said in a statement.

Charged particles in the solar wind can interrupt GPS signals and power systems, as well as create dazzling auroras.

The magnetosphere is the planet's first line of defense against the solar wind. Scientists knew that this plasma stream occasionally breached the magnetosphere near the equator, where the Earth's magnetic field is roughly parallel to the magnetic field in the solar wind. The new study, published Aug. 29 in the Journal of Geophysical Research, found that these breaks can happen under a wider range of conditions.

"That suggests there is a 'sieve-like' property of the magnetopause [the outer edge of the magnetosphere] in allowing the solar wind to continuously flow into the magnetosphere," Goldstein said.

Plasma swirls break magnetic field

The European Space Agency's Cluster mission, a set of four satellites that fly in close formation through the Earth's magnetic field, gathered the data that show how the solar wind can get through. Equipped with state-of-the-art instruments for measuring electric and magnetic fields, the Cluster satellites fly in and out of the magnetosphere and document the microscopic magnetic interactions between the Earth and the sun.

From 2006 Cluster observations, scientists found that huge swirls of plasma along the magnetopause could help the solar wind penetrate the magnetosphere when the terrestrial and solar wind magnetic fields were aligned. Those swirls of plasma are known as Kelvin-Helmholtz waves, and they can be 24,850 miles (40,000 kilometers) in diameter.

As Kelvin-Helmholtz waves slide past the magnetopause, they can create giant vortices, similar to how wind blowing across the ocean causes waves. The huge waves can spontaneously break and reconnect magnetic field lines, creating openings that let the solar wind slip through.

'Not a perfect magnetic bubble'

The new findings suggest that these magnetic field line breaks can also occur where the terrestrial and solar wind magnetic fields are perpendicular, at high latitudes near the poles.

The alignments of the solar wind magnetic field and Earth's magnetic field are key factors. A perpendicular alignment makes the boundary between the two fields less stable and likely generates more Kelvin-Helmholtz waves — and more magnetic field breaches. [Video: Sun's Energy Shocks Earth's Magnetic Field]

"We found that when the [solar wind] magnetic field is westward or eastward, magnetopause boundary layers at higher latitude become most subject to Kelvin-Helmholtz instabilities, regions quite distant from previous observations of these waves," Kyoung-Joo Hwang, a researcher at NASA's Goddard Space Flight Center who led the study, said in a statement.

"In fact, it's very hard to imagine a situation where solar wind plasma could not leak into the magnetosphere, since it is not a perfect magnetic bubble," Hwang said.

This story was provided by OurAmazingPlanet, a sister site to LiveScience. Follow OurAmazingPlanet for the latest in Earth science and exploration news on Twitter @OAPlanet. We're also on Facebook & Google+.

The solution to a long-standing puzzle, why magnetic north sits off the coast of Canada, rather than at the North Pole, may have been found in the strange, lopsided nature of Earth's inner core.

The inner core is a ball of solid iron about 760 miles (1,220 kilometers) wide. It is surrounded by a liquid outer core (mostly iron and nickel), a rocky, viscous mantle layer and a thin, solid crust.

As the inner core cools, crystallizing iron releases impurities, sending lighter molten material into the liquid outer core. This upwelling, combined with the Earth's rotation, drives convection, forcing the molten metal into whirling vortices. These vortices stretch and twist magnetic field lines, creating Earth’s magnetic field. Currently, the center of the field, called an axis, emerges in the Arctic Ocean west of Ellesmere Island, about 300 miles (500 kilometers) from the geographic North Pole.

In the last decade, seismic waves from earthquakes revealed the inner core looks like a navel orange, bulging slightly more on its western half. Geoscientists recently explainedthe asymmetry by proposing a convective loop: The inner core might be crystallizing on one half and melting on the other.

Peter Olson and Renaud Deguen, geophysicists at Johns Hopkins University, set out to test this theory, called translational instability. They ran numerical models simulating the forces that generate Earth’s magnetic field, and included a lopsided inner core.

Olson and Deguen found that adding inner-core asymmetry shifted magnetic north away from the center of the Earth, into the cooling hemisphere. Convection was stronger there, as was the magnetic field.

"The lopsided growth of the inner core makes convection in the outer core a little bit lopsided, and that then induces the geomagnetic field to have this lopsided or eccentric character too," Olson told OurAmazingPlanet. Olson and Deguen's research was detailed online July 1 in the journal Nature Geoscience.

Geophysicist Bruce Buffett said Olson and Deguen’s research is intriguing, but there are still questions about the underlying theory. "It's an interesting result, but we don't know for sure the inner core is translating. The model does a good job at explaining some but not all of the features of the inner core," said Buffett, a professor at the University of California, Berkeley, who was not involved with the research.

Olson points out that his numerical model offers a real-world proof of the theory. Magnetic particles trapped and aligned in rocks reveal that the magnetic north pole wandered around the Western Hemisphere over the past 10,000 years, and circled the Eastern Hemisphere before that — a result mirrored by the numerical test. Gathering a longer, more detailed record of the magnetic field's behavior, Olson said, could reveal whether the inner core acts as researchers predict.

"The key question for interesting ideas like translational instability is, 'Can we test it?'" Olson said. "What we're doing is proposing a test, and we think it's a good test because people can go out and look for eccentricity in the rock record and that will either confirm or shoot down this idea."

This article was provided by OurAmazingPlanet, a sister site to LiveScience.

The end of the world as we know it could come in any number of ways, depending on who you ask. Some people believe global cataclysm will occur when Earth's magnetic poles reverse. When north goes south, they say, the continents will lurch in one direction or the other, triggering massive earthquakes, rapid climate change and species extinctions.

The geologic record shows that hundreds of pole reversals have occurred throughout Earth's history; they happen when patches of iron atoms in Earth's liquid outer core become reverse-aligned, like tiny magnets oriented in the opposite direction from those around them. When the reversed patches grow to the point that they dominate the rest of the core, Earth's overall magnetic field flips. The last reversal happened 780,000 years ago during the Stone Age, and indeed there's evidence to suggest the planet may be in the early stages of a pole reversal right now.

But should we really fear this event? What will actually happen when north-pointing compasses make a 180-degree turn toward Antarctica? Will the continents tear themselves apart, or are we in store for much more mundane changes?

Weak field

"The most dramatic changes that occur when the poles reverse is a very large decrease of the total field intensity," said Jean-Pierre Valet, who conducts research on geomagnetic reversals at the Institute of Earth Physics of Paris. [5 Ways the World Will Change Dramatically this Century]

Earth's magnetic field takes between 1,000 and 10,000 years to reverse, and in the process, it greatly diminishes before it re-aligns. "It's not a sudden flip, but a slow process, during which the field strength becomes weak, very probably the field becomes more complex and might show more than two poles for a while, and then builds up in strength and [aligns] in the opposite direction," said Monika Korte, the scientific director of the Niemegk Geomagnetic Observatory at GFZ Potsdam in Germany.

The scientists say it's the weak in-between phase that would be roughest on Earthlings.

According to John Tarduno, professor of geophysics at the University of Rochester, a strong magnetic field helps protect Earth from blasts of radiation from the sun. "Coronal mass ejections (CMEs) occasionally occur on the Sun, and sometimes hurtle directly toward Earth," Tarduno said. "Some of the particles associated with CMEs can be blocked by Earth's magnetic field. With a weak field, this shielding is less efficient."

The charged particles bombarding Earth's atmosphere during solar storms would punch holes in Earth's atmosphere, and this could hurt humans. "Ozone holes, like that over Antarctica (which today are due to an entirely different cause related to man) could form as solar particles interact with the atmosphere in a cascade of chemical reactions. These 'holes' would not be permanent, but might be present on one- to 10-year timescales — arguably important enough to be a concern in terms of skin cancer rates," Tarduno said. [Will Sunscreen Protect You from the Upcoming Solar Flares?]

Valet agrees that a weak magnetic field could lead to the formation of ozone holes. He wrote a paper last year proposing a direct link between the demise of Neanderthals, our evolutionary cousins, and a significant decrease of the geomagnetic field intensity that occurred exactly at the same period. (That time, the lead-up to a geomagnetic reversal appears to have been "aborted"; the field weakened but didn't end up flipping.)

Other scientists aren't convinced that there's a connection between pole reversals and species extinctions. "Even if the field becomes very weak, at the Earth's surface we are shielded from radiation by the atmosphere. Similarly as we cannot see or feel the presence of the geomagnetic field now, we most likely would not notice any significant change from a reversal," Korte said.

Our technology definitely would be in danger, however. Even now, solar storms can damage satellites, cause power outages and interrupt radio communications. "These kinds of negative influences clearly will increase if the magnetic field and thus its shielding function became significantly weaker, e.g. during a reversal, and it will be important to find mitigation strategies," she told Life's Little Mysteries.

One additional worry is that a weakening and eventual reversal in the field would disorient all those species that rely on geomagnetism for navigation, including bees, salmon, turtles, whales, bacteria and pigeons. There is no scientific consensus on how those creatures would cope.

Continental shifts?

Many of the disaster scenarios associated with geomagnetic pole reversals in popular imagination are pure fantasy, the scientists said. There definitely won't be any break-up or shift of the continents.

The first proof is the geologic record. When the last pole switch happened, "no worldwide shifting of continents or other planet-wide disasters occurred, as geoscientists can testify to from fossil and other records," said Alan Thompson, head of geomagnetism at the British Geological Survey.

The scientists explained that changes in the Earth's liquid core happen on a completely different distance and timescale than convection in the Earth's mantle (which causes Earth's tectonic plates to shift, moving the continents). The liquid core does indeed touch the bottom of the mantle, but it would take tens of millions of years for changes in the core to propagate up through the mantle and influence the motion of the tectonic plates. In short, "there is no evidence from the geological past and in my opinion also no conceivable method that magnetic reversals couldtrigger Earthquakes," Korte said.

Sooner or later

The geomagnetic field is currently weakening, possibly because of a growing patch of reverse-alignment in the liquid core deep beneath Brazil and the South Atlantic. According to Tarduno, the strength of Earth's magnetic field "has been decreasing for at least 160 years at an alarming rate, leading some to speculate that we are heading toward a reversal."

The reversal might happen, or it might be aborted — Earth is too complex a system for scientists to know which outcome to expect. Either way, the process will drag on over the next few thousand years, giving us time to adjust to the changes. 

Follow Natalie Wolchover on Twitter @nattyover. Follow Life's Little Mysteries on Twitter @llmysteries, then join us on Facebook.

As you move upward from Earth's surface and through the layers of its atmosphere, the air becomes thinner and thinner until you reach the diffuse boundary where the atmosphere meets the seeming void of outer space.

But the space surrounding Earth is anything but barren: It seethes with charged particles that flow around the planet's magnetic field, moving energy around, creating electric currents and producing the spectacular auroras that dance across polar skies.

Many of these particles stream in from the solar wind that blows out from the surface of the sun, but others come from the Earth's atmosphere itself. Unlike the hotter hydrogen coming from the sun, Earth's upper atmosphere generally supplies cooler oxygen ions that course outward along Earth's magnetic field lines.

This "ion outflow," as it is called, occurs continuously, but is especially strong during periods when there is more solar activity such as solar flares and coronal mass ejections that burst off the sun and move toward Earth. Such activity drives oxygen ions out of our planet's upper atmosphere, particularly in regions where aurora displays are strong. [Infographic: Earth's Atmosphere Top to Bottom]

"These ion outflow events are important because they help us understand the space weather environment around Earth," said Doug Rowland, the principal investigator for FASTSAT's Plasma Impedance Spectrum Analyzer (PISA), at NASA's Goddard Space Flight Center in Greenbelt, Md. "The heavy ions flowing away from Earth can act as a brake, or damper, on incoming energy from the solar wind. The flow also indicates ways in which planets can lose their atmospheres – something that happens slowly on Earth, but more quickly on smaller planets with weaker magnetic fields, like Mars."

Earlier this year, the NASA FASTSAT satellite mission got a detailed picture of this dynamic region and the particles swirling around it during a particularly well-defined event; the data gleaned from it are helping scientists better understand just what goes on there.

FASTSAT's Miniature Imager for Neutral Ionospheric Atoms and Magnetospheric Electrons (MINI-ME) instrument has been successfully spotting such outflows since the instrument first began to collect data in winter 2010. The instrument counts ions as it moves through a part of Earth's atmosphere called the ionosphere. This is the region where the particles gain enough speed and energy to overcome Earth's gravity, so it's an ideal place to study the first step in the outflow process.

Late on March 31, 2011, the FASTSAT spacecraft flew through an ion outflow with well-defined areas of increased fast-moving, or "energetic," particles.

Simultaneous observations from PISA, which measures the density of material in the atmosphere, also showed that this was a highly structured auroral zone.

The FASTSAT data were compared to that from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), a mission managed by the Johns Hopkins Applied Physics Laboratory, which measures current flow and magnetic features through a network of instruments placed on commercial satellites owned by Iridium Communications. AMPERE data showed current structures that were also consistent with what is expected for an auroral zone.

"This is just one event," said Michael Collier, principal investigator for MINI-ME also at NASA Goddard. "But it helps confirm the idea that the current and ion outflows are all connected. As we continue to go through the data, there will be many more events to follow," he explained. "We'd like to be able to pin down the origin of all these mechanisms in the ionosphere."

The giants that migrate farther than any other mammal on Earth, humpback whales, do so with mysterious, extraordinary accuracy, veering off course by less than 1 degree over hundreds of miles, scientists find.

Humpback whales (Megaptera novaeangliae) regularly swim roughly 3,000 miles (5,000 kilometers) between breeding and feeding grounds. However, a record-setting female humpback was recently discovered traveling from Brazil to Madagascar, a voyage of at least 6,090 miles (9,800 km) — the longest documented migration by any mammal ever.

To learn more about these remarkable migrations, scientists embedded radio tags in the skin and blubber of 16 humpbacks and used satellites to track them from 2003 to 2010. (The tags, about 8 to 12 inches long — 20 to 30 centimeters — were designed to fall off their bodies over time.) [Images of whales being tagged]

The humpbacks were tracked migrating southeastward from Brazil in the Atlantic Ocean and New Caledonia in the Pacific Ocean and west-northwestward from the Pacific island of Rarotonga. [Top 10 Most Incredible Animal Journeys]

"The Brazil and New Caledonia whales were clearly migrating away from low-latitude calving grounds towards high-latitude feeding grounds," said researcher Travis Horton, an environmental scientist at the University of Canterbury in New Zealand. "The movements of the Rarotonga whales are anomalous and remain difficult to explain, as we would expect them to be moving in an overall southerly direction by late winter."

The whales each traveled distances of at least 120 miles (200 km). They moved in astonishingly straight lines, with most straying off course by 1 degree or less. The humpback that swam the most, a 28-day voyage of 1,386 miles (2,232 km), veered just 0.4 degrees off.

It remains a mystery how these whales are capable of such exceptional precision. For instance, buoys along their routes showed that highly variable sea currents were capable of significantly deflecting their headings.

Animals are known to figure out direction over long distances from the Earth's magnetic field or the direction of the sun. For instance, researchers of tiger sharks and thresher sharks recently said cues from Earth's magnetic fields may what enables those sharks to orient themselves and travel spot-on toward a far target.

In the case of the humpback whales, however, magnetic cues by themselves might not help, as the Earth's magnetic field varied widely along each whale's voyage, with magnetic north changing by as much as 12 percent and as little as 0.5 percent across these journeys. Similarly, the sun alone could not explain the whales' success. Humpbacks from the same area were found to follow similar headings despite seeing the sun in different positions in the sky, and they also followed different headings despite seeing the sun in similar positions.

"Although we saw no clear relationship between solar and magnetic directional cues and whale headings, it is entirely possible that they are using both the sun and magnetic field in a coupled system of orientation," Horton said.

The scientists detailed their findings online April 20 in the journal Biology Letters.

"We have a reasonable handle now on what they are doing, but very little information on how they are doing it," Horton told Live Science. "As more data becomes available, we will transition from 'what they're doing' studies to more process-oriented 'how they're doing it' interpretations."

Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

Whale Tag

The Cook Islands whale research team tags a humpback whale as it surfaces off the island of Rarotonga. The whales are being tagged as part of "The Great Whale Trail." The project is a collaboration between Greenpeace and Nan Hauser, who studies humpback whales in the Cook Islands.

Straight and Arrow

Researhers have found humpback whales, like this one off Rarotonga, Cook Islands in the South Pacific, are extremely precise navigators.

Whale Tail

Marine mammologist Ygor Geyer tags a humpback whale while the director of the Cook Islands whale research team, Nan Hauser, records the event in Rarotonga, Cook Islands.

Tagging Humpbacks

Humpback whales (Megaptera novaeangliae) regularly swim roughly 3,000 miles (5,000 kilometers) between breeding and feeding grounds.

Marine Giant

Humpback whales can reach some 40 to 50 feet in length, here one is shown along the Cook Islands in the South Pacific.

Behemoth Undertaking

The tags embedded in the skin and blubber of humpback whales are about 8 to 12 inches long and naturally fall off over time.

Radio Tag

The Cook Island whale research team tag a humpback whale as it surfaces off Rarotonga, Cook Islands. The radio tag is embedded in the skin and blubber so scientists can track the animal's movements.

Every so often, Earth's magnetic field flips on its head, turning the magnetic North Pole into the South Pole and vice versa.

It last happened 780,000 years ago, and is predicted to occur again in about 1,500 years ... maybe. The overall frequency is hard to predict — there was one period in Earth's history when the field didn't reverse for 30 million years.

Why these flip-flops happen at all is a great riddle, but a new hypothesis on the origins of the magnetic field could shed light on the reason.

How it works

Earth's magnetic field is really two fields with two separate sources, argues paleomagnetist Kenneth Hoffman of California Polytechnic State University in San Luis Obispo and geochronologist Brad Singer of the University of Wisconsin, Madison, in a paper published in the Sept. 26 issue of the journal Science.

One component of the field, the stronger part, is the north-south pointing "axial dipole" magnetic field, which can be pictured as the kind of field that would be created by a giant bar magnet inside the Earth.

There is also a weaker field spread around the planet, not positioned along the north-south axis. The researchers suggest this weak field is created closer to the surface of Earth's outer core, while the stronger north-south field is produced throughout the core, including the deepest parts.

Both fields are thought to result from the movement of electrons from hot iron atoms in the convective flow of the core, which is more of a liquid than a solid. The movement of the charged particles through the planet creates a magnetic field just as the movement of an electric current through a wire does.

The researchers suggest that the sporadic reversal of Earth's magnetic field occurs when the axial dipole field weakens, leaving the weaker, more disperse field intact.

"The field is not always stable, the convection and the nature of the flow changes, and it can cause the dipole that’s generated to wax and wane in intensity and strength," Singer said. "When it becomes very weak, it's less capable of reaching to the surface of the Earth, and what you start to see emerge is this non-axial dipole, the weaker part of the field that's left over."

How can they know that?

To figure this out, Hoffman and Singer analyzed remnants of lava that poured out of volcanoes in Tahiti and Germany between 500,000 and 700,000 years ago. The lava contains an iron-rich mineral called magnetite. When the hot lava is erupted, the iron atoms' electrons spin in random directions, but as it cools down the electron spins freeze pointing in the direction of the planet's magnetic field lines.

At times when the Earth's magnetic dipole field was strong, the spins in both Tahiti and Germany pointed toward the magnetic North Pole. However, when the dipole field was weakening or preparing to reverse, the spins were left to be guided by the strongest nearby magnetic field lines from the weaker field that was left over, which were different in Germany compared to Tahiti.

The finding shows that when the main element of Earth's magnetic field is weak, smaller local magnetic pulls kick in. By studying where these local pulls are strongest, the researchers can map out this second layer of field and learn how it differs from the stronger field.

Forward flip

Ultimately, scientists hope to have a better handle on these issues by the time our planet's field flips again.

"The magnetic field is one of the most fundamental features of the Earth," Singer told LiveScience. "But it's still one of the biggest enigmas in science. Why [the flip] happens is something people have been chasing for more than a hundred years."

When the next reversal comes, it probably won't inflict much damage to life on Earth, Singer said. Though we could expect a slight increase in damaging cosmic radiation, which is usually repelled by the magnetic field, it shouldn't be enough to cause serious harm. And though magnetic north and south poles will switch spots, the seasons and other cycles on the planet are primarily due to Earth's position relative to the sun, which wouldn't change significantly. All in all, the flip is nothing that our planet hasn't faced many times before.

"The magnetic field has reversed itself hundreds, if not thousands, of times," Singer said. "Right now, the axial dipole is waning in strength, so we might experience a field reversal in the next two millennia if it continues to weaken at the current rate."

• Top Ten Strangest Things in Space
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• 101 Amazing Earth Facts

Captain Cook's Pacific Ocean voyage logs have proven to be quite valuable, but not on eBay.

Old ship logs tell the tale of Earth's magnetic field and suggest that the current decline in strength may be a recent phenomenon and not necessarily a trend.

The Earth is like a magnet with two poles. Magnetic field lines travel between the North and South poles and are generated by the movement of molten iron in Earth's core.

This magnetic field has weakened by 5 percent each century since 1840, when the first accurate measurements were made. But a new study looking at the magnetic field strength between 1590 and 1840 finds the field was relatively stable during that time.

The modeling of historical magnetic data started in the early 1980's by study team member David Gubbins, a researcher from University of Leeds in the United Kingdom.

Gubbins and colleagues started with readily available data like those in the logs of famed English sailor and explorer, James Cook.

"[We then] progressed to searching archives in Europe, including finding 50,000 'lost' 18th century measurements in the East India Company Archives in London," Gubbins told LiveScience.

Using the old sailing ships' logbooks, which recorded magnetic field directions useful in reconstructing field strength, and combining it with a global model of directions, they produced 250 years worth of measurement data.

This recent finding suggests that the current decline in field strength comes from growing and migrating patches of reverse magnetic flux in the southern hemisphere.

The Earth's magnetic field has reversed many times. This happens because magnetic poles can move around and trade places. Scientists do not know when the next flip will occur.

The findings of this study are detailed in the May 12 issue of the journal Science.

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• When North Becomes South: New Clues to Earth's Magnetic Flip-Flops
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