Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior to where it meets the solar wind, a stream of charged particles emanating from the Sun. Its magnitude at the Earth's surface ranges from 25 to 65 microtesla (0.25 to 0.65 gauss). Roughly speaking it is the field of a magnetic dipole currently tilted at an angle of about 10 degrees with respect to Earth's rotational axis, as if there were a bar magnet placed at that angle at the center of the Earth. Unlike a bar magnet, however, Earth's magnetic field changes over time because it is generated by a geodynamo (in Earth's case, the motion of molten iron alloys in its outer core).
The North and South magnetic poles wander widely, but sufficiently slowly for ordinary compasses to remain useful for navigation. However, at irregular intervals averaging several hundred thousand years, the Earth's field reverses and the North and South Magnetic Poles relatively abruptly switch places. These reversals of the geomagnetic poles leave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past. Such information in turn is helpful in studying the motions of continents and ocean floors in the process of plate tectonics.
The magnetosphere is the region above the ionosphere and extends several tens of thousands of kilometers into space, protecting the Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects the Earth from harmful ultraviolet radiation. Read More
Coronal Mass Ejections (CMEs) reach Earth affecting planetary magnetics, sparking geomagnetic storms, shifting ocean and jet stream currents in the Pacific Ring of Fire, creating unusual and extreme global weather patterns, creating unstoppable Earth changes, and affecting the behavior patterns of all sentient life forms.
Just what sustains Earth's magnetic field anyway? PhysOrg - June 1, 2016
Earth's magnetic field shields us from deadly cosmic radiation, and without it, life as we know it could not exist here. The motion of liquid iron in the planet's outer core, a phenomenon called a "geodynamo," generates the field. But how it was first created and then sustained throughout Earth's history has remained a mystery to scientists.Our planet accreted from rocky material that surrounded our Sun in its youth, and over time the most-dense stuff, iron, sank inward, creating the layers that we know exist today - core, mantle, and crust. Currently, the inner core is solid iron, with some other materials that were dragged along down during this layering process. The outer core is a liquid iron alloy, and its motion gives rise to the magnetic field.
Missing link in metal physics explains Earth's magnetic field Science Daily - January 28, 2015
Earth's magnetic field shields the life on our planet's surface from cosmic rays. It is generated by turbulent motions of liquid iron in Earth's core. Iron is a metal, which means it can easily conduct a flow of electrons. New findings show that a missing piece of the traditional theory explaining why metals become less conductive when they are heated was needed to complete the puzzle of this field-generating process.
Earth's magnetic field could flip within a human lifetime Science Daily - October 14, 2014
Earth's last magnetic reversal took place 786,000 years ago and happened very quickly, in less than 100 years -- roughly a human lifetime. The rapid flip, much faster than the thousands of years most geologists thought, comes as new measurements show the planet's magnetic field is weakening 10 times faster than normal and could drop to zero in a few thousand years.
Earth's Magnetic Field Is Weakening 10 Times Faster Now Live Science - July 8, 2014
Earth's magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm. The biggest weak spots in the magnetic field - which extends 370,000 miles (600,000 kilometers) above the planet's surface - have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites - three separate satellites floating in tandem.
Earth's 6-Year Twitch Changes Day Length Live Science - July 10, 2013
Periodic wobbles in Earth's core change the length of a day every 5.9 years. Teasing out this subtle cycle, which subtracts and adds mere milliseconds to each day, also revealed a match between abrupt changes in the length of day and Earth's magnetic field. During these short-lived lurches in the magnetic field intensity, events called geomagnetic jerks, Earth's day also shifts by 0.1 millisecond, the researchers report. Since 1969, scientists have detected 10 geomagnetic jerks lasting less than a year. Seemingly negligible, these fleeting variations are mighty to those who study the planet and its core. All of a sudden, a planet changes its spin like a figure skater open or closing her arms. The rotational effect helps scientists understand what's happening inside the Earth's core. Shifts in the magnetic field also provide clues to the inaccessible iron core. But their source remains a mystery.
Why Earth's Magnetic Field Is Wonky Live Science - July 18, 2012
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 EarthÕs 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.
Can humans sense the Earth's magnetism? PhysOrg - June 21, 2011
For migratory birds and sea turtles, the ability to sense the Earth's magnetic field is crucial to navigating the long-distance voyages these animals undertake during migration. Humans, however, are widely assumed not to have an innate magnetic sense.
Humans May Have 'Magnetic' Sixth Sense Live Science - June 21, 2011
Humans may have a sixth sense after all, suggests a new study finding that a protein in the human retina, when placed into fruit flies, has the ability to detect magnetic fields.
Human eye protein senses Earth's magnetism BBC - June 21, 2011
A light-sensitive protein in the human eye has been shown to act as a "compass" in a magnetic field, when it is present in flies' eyes.
Reading Earth's magnetic history PhysOrg - March 4, 2011
In order to date environmental events from Earth's history such as meteorite impacts or climate change - geologists have long studied variations in slow-growing seafloor sedimentary rocks called ferromanganese crusts that build up in layers over the eons. The layers can be dated by various means, such as by analyzing radioactive isotopes, but those methods don't provide accurate dating on small scales: a millimeter of rock, for example, can include information that spans as much as hundreds of thousands of years.
Compass Direction, True North Parting Ways Discovery - March 4, 2011
Earth's magnetic field is carting away toward Russia at a rate of about 40 miles a year. The shift widens the distance between true north and magnetic north, which is the direction a compass needle points. The phenomenon is normal, though it does have implications for modern life. The planet's magnetic field is on the move, a normal enough phenomenon, but one that has some rather bizarre implications, such as the need to renumber airport runways. Tampa International Airport on Florida's west coast just finished renaming its three runways, a laborious project that interrupted airport traffic for a month while runways were shut down for repainting.
African rocks record ancient magnetic field BBC - May 4, 2010
Scientists have managed to push back the date for the earliest known presence of a magnetic field on Earth by about 250 million years.
Monarch Butterflies Reveal a Novel Way in Which Animals Sense Earth's Magnetic Field Science Daily - January 27, 2010
Building on prior investigation into the biological mechanisms through which monarch butterflies are able to migrate up to 2,000 miles from eastern North America to a particular forest in Mexico each year, neurobiologists at the University of Massachusetts Medical School (UMMS) have linked two related photoreceptor proteins found in butterflies to animal navigation using the Earth's magnetic field.
Robins can see Earth's magnetic field Telegraph.co.uk - October 29, 2009
he information, relayed to a specialized light-processing region of the brain called ''cluster N'', helps the robin find its way on migration flights. Experts know birds possess an internal magnetic compass, but there is disagreement about what form it takes. One idea is that tiny magnets in the beak wired to the nervous system detect lines of magnetic force. Another is that magnetic fields are ''seen'' via the eyes using a light-sensitive mechanism. The new research suggests that, for robins at least, the second theory is probably correct. German scientists studied 36 European robins and found birds with damage to ''cluster N'' were unable to orientate themselves using the Earth's magnetic field. But damage to another nerve channel necessary for a beak-sensing system had no effect.
'Magnetricity' observed and measured for the first time PhysOrg - October 18, 2009
The magnetic equivalent of electricity in a 'spin ice' material: atom sized north and south poles in spin ice drift in opposite directions when a magnetic field is applied. A magnetic charge can behave and interact just like an electric charge in some materials, according to new research led by the London Centre for Nanotechnology.
Ancient Earth's Magnetic Field Was Structured Like Today's Two-pole Model Science Daily - October 5, 2009
Princeton University scientists have shown that, in ancient times, the Earth's magnetic field was structured like the two-pole model of today, suggesting that the methods geoscientists use to reconstruct the geography of early land masses on the globe are accurate. The findings may lead to a better understanding of historical continental movement, which relates to changes in climate. By taking a closer look at the 1.1 billion-year-old volcanic rocks on the north shore of Lake Superior, the researchers have found that Earth's ancient magnetic field was a geocentric axial dipole -- essentially a large bar magnet centered in the core and aligned with the Earth's spin axis.
Shifts in Earth's Magnetic Field Driven by Oceans? National Geographic - June 23, 2009
The flow of seawater across Earth's surface could be responsible for small fluctuations in the planet's magnetic field, a controversial new study says. If so, the research would challenge the widely accepted theory that Earth's magnetic field is generated by a churning molten core, or dynamo, in the planet's interior.
Rare Magnetar Discovered: Giant Eruption Reveals 'Dead' Star Science Daily - June 16, 2009
NASA's Swift satellite reported multiple blasts of radiation from a rare object known as a soft gamma repeater, or SGR. Now, astronomers report an in-depth study of these eruptions using the European Space Agency's XMM-Newton and International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellites.
Giant Eruption Reveals 'Dead' Star Space Daily - June 18, 2009
An enormous eruption has found its way to Earth after traveling for many thousands of years across space. The dead star belonging to a rare group: the magnetars.
Reversals of Earth's Magnetic Field Explained by Small Core Fluctuations PhysOrg - April 23, 2009
Based on studies of old volcanic basalt, scientists know that the EarthÕs magnetic field reverses at irregular intervals, ranging from tens of thousands to millions of years. Volcanic basalt rock contains magnetite, and when the rock cools, its magnetic properties are frozen, recording the Earth's magnetic field of the time. With this data, scientists estimate that the last magnetic field reversal occurred about 780,000 years ago.
"Warm Plasma Cloak" Discovered Enveloping Earth National Geographic - January 7, 2009
The magnetosphere - the shield of ions and electrons that envelops Earth
extends far beyond the atmosphere, defending the planet from the harmful solar wind.
Magnetic-Shield Cracks Found; Big Solar Storms Expected National Geographic - December 17, 2008
An unexpected, thick layer of solar particles inside Earth's magnetic field suggests there are huge breaches in our planet's solar defenses. These breaches indicate that during the next period of high solar activity, due to start in 2012, Earth will experience some of the worst solar storms seen in decades.
Leaks Found in Earth's Protective Magnetic Field Live Science - December 17, 2008
Scientists have found two large leaks in Earth's magnetosphere, the region around our planet that shields us from severe solar storms. The leaks are defying many of scientists' previous ideas on how the interaction between Earth's magnetosphere and solar wind occurs: The leaks are in an unexpected location, let in solar particles in faster than expected and the whole interaction works in a manner that is completely the opposite of what scientists had thought.
A Giant Breach in Earth's Magnetic Field NASA - December 16, 2008
NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist. Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms. But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.
Lava flows reveal clues to magnetic field reversals PhysOrg - September 25, 2008
Ancient lava flows are guiding a better understanding of what generates and controls the Earth's magnetic field - and what may drive it to occasionally reverse direction. The main magnetic field, generated by turbulent currents within the deep mass of molten iron of the Earth's outer core, periodically flips its direction, such that a compass needle would point south rather than north. Such polarity reversals have occurred hundreds of times at irregular intervals throughout the planet's history - most recently about 780,000 years ago - but scientists are still trying to understand how and why.
Earth's Core, Magnetic Field Changing Fast, Study Says National Geographic - July 1, 2008
Rapid changes in the churning movement of Earth's liquid outer core are weakening the magnetic field in some regions of the planet's surface, a new study says. "What is so surprising is that rapid, almost sudden, changes take place in the Earth's magnetic field," said study co-author Nils Olsen, a geophysicist at the Danish National Space Center in Copenhagen.
Birds Can "See" Earth's Magnetic Field National Geographic - September 27, 2007
To find north, humans look to a compass. But birds may just need to open their eyes, a new study says. Scientists already suspected birds' eyes contain molecules that are thought to sense Earth's magnetic field. In a new study, German researchers found that these molecules are linked to an area of the brain known to process visual information. In that sense, "birds may see the magnetic field," said study lead author Dominik Heyers, a biologist at the University of Oldenburg. Human-made compasses work by using Earth as an enormous magnet and orienting a tiny magnet attached to a needle to the planet's north and south poles.
Magnetic Field Weakening in Stages, Old Ships' Logs Suggest National Geographic - May 12, 2006
Earth's magnetic field is weakening in staggered steps, a new analysis of centuries-old ships logs suggests.The finding could help scientists better understand the way Earth's magnetic poles reverse. The planet's magnetic field flips - north becomes south and vice versa - on average every 300,000 years. However, the actual time between reversals varies widely. The field last flipped about 800,000 years ago, according to the geologic record. Since 1840, when accurate measures of the intensity were first made, the field strength has declined by about 5 percent per century. If this decline is continuous, the magnetic field could drop to zero and reverse sometime within the next 2,000 years. But the field might not always be in steady decline, according to a new study appearing in tomorrow's issue of the journal Science. The data show that field strength was relatively stable between 1590 and 1840.
Geomagnetic flip may not be random after all PhysicsWeb - March 22, 2006
One of the most fascinating natural phenomena on Earth is the flipping of its magnetic field, which has occurred hundreds of times in the last 160 million years. When the magnetic field flips, the North Pole becomes the South Pole and vice versa. The last time this happened was some 780,000 years ago, so we could be heading for another reversal soon. Now, physicists in Italy have found that the frequency of these polarity reversals is not random as previously thought but occurs in clusters, revealing some kind of "memory" of previous events
Movement of North Magnetic Pole is accelerating PhysOrg - December 9, 2005
After some 400 years of relative stability, Earth's North Magnetic Pole has moved nearly 1,100 kilometers out into the Arctic Ocean during the last century and at its present rate could move from northern Canada to Siberia within the next half-century. If that happens, Alaska may be in danger of losing one of its most stunning natural phenomena Š the Northern Lights.
Pulsar Gives Insight On Ultra Dense Matter And Magnetic Fields Science Daily - December 20, 2004
A long look at a young pulsar with NASA's Chandra X-ray Observatory revealed unexpectedly rapid cooling, which suggests that it contains much denser matter than previously expected. The pulsar's cool temperature and the vast magnetic web of high-energy particles that surrounds it have implications for the theory of nuclear matter and the origin of magnetic fields in cosmic objects.
Why Does Earth's Magnetic Field Flip? National Geographic - September 27, 2004
Earth's magnetic field has flipped many times over the last billion years, according to the geologic record. But only in the past decade have scientists developed and evolved a computer model to demonstrate how these reversals occur. Scientists believe Earth's magnetic field is generated deep inside our planet. There, the heat of the Earth's solid inner core churns a liquid outer core composed of iron and nickel. The churning acts like convection, which generates electric currents and, as a result, a magnetic field. This magnetic field shields most of the habited parts of our planet from charged particles that emanate from space, mainly from the sun. The field deflects the speeding particles toward Earth's Poles
Earth's Magnetic Field Is Fading National Geographic - September 9, 2004
The Earth's Magnetics fields appear to be reversing...
Today it is about 10 percent weaker than it was when German mathematician Carl Friedrich Gauss started keeping tabs on it in 1845, scientists say. If the trend continues, the field may collapse altogether and then reverse. Compasses would point south instead of north.
The Earth's magnetic field is fading BBC - December 31, 2003
Scientists have known for some time that the Earth's magnetic field is fading. Like a Kryptonite-challenged Superman, its strength has steadily and mysteriously waned, leaving parts of the planet vulnerable to increased radiation from space. Some satellites already feel the effects. What is uncertain is whether the weakened field is on the way to a complete collapse and a reversal that would flip the North and South Poles. Compasses pointing North would then point South.
Earth's magnetic north pole is racing away from North America. NASA - December 29, 2003
Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years In 1904, Roald Amundsen found the pole again and discovered that it had moved at least 50 km since the days of Ross. The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating to 40 km per year. At this rate it will exit North America and reach Siberia in a few decades.
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