The movement of the iron core generates electricity, which results in a magnetic orientation of the entire planet. Scientists can trace the magnetic history of our planet through cooled lava. Because the planet’s magnetism deflects solar radiation, it allows life to exist on Earth. In fact, throughout the history of our planet, the poles have even changed their position several times, and the magnetic field strength has increased and decreased. The rocks indicate that Earth had a strong magnetic field 3.7 billion years ago, but scientists are not sure where the field might have come from. Magnetized boulders have also been discovered on the Moon.
Life could not have formed without the Earth’s magnetic field, which arises from molten heavy metals seething in its core
Our planet is one giant magnet with a diameter of about 8,000 miles. The magnetic force—the electrical interaction between magnetically charged metals in the Earth’s core—extends thousands of miles into space. This magnetosphere blocks powerful solar radiation that would otherwise destroy our atmosphere and life on the planet. In fact, solar winds actually blow the magnetic shell off the Earth in the shape of a tail.
A visible side effect of our magnetic sun protection is the Aurora, or Northern and Southern Lights. The blue-green glow is caused by charged solar particles falling into the upper atmosphere at speeds of up to 45 million miles per hour. Fortunately, our magnetic field deflects the solar wind toward the Earth’s poles. Along the way, particles in our ionosphere fluoresce, causing a light show. Astronauts can see the aurora from space.
Liquid metals such as iron in the outer core move. Because of the Earth’s rotation, we have “moving, magnetically charged metals,” says astrophysicist Neil deGrasse Tyson in a YouTube short. “When you have moving metal, you create what is called a dynamo, and in a dynamo, you actually create a magnetic field from scratch. This is why cooled old, dead planets have no magnetic fields. For example, Mars has no magnetic field to speak of.” Today, the Red Planet has no molten core, and its magnetic field declined sharply about 3.8 billion years ago for unknown reasons. This left the planet and all life that might exist on it open to harmful solar radiation.
Imagine water boiling in a heated pan. It continues to boil due to convective forces that transfer heat through the liquid. Likewise, the hot molten core of heavy metals bubbles, spurred on by the planet’s rotation. During this constant movement, an electrical current hundreds of miles wide is generated in the heavy metals, flowing at thousands of miles per hour.
Paleomagnetic scientists who study this phenomenon sample and date rocks from Earth’s moving mid-ocean ridges, where tectonic plates form as lava erupts as it spreads and cools. Minerals emerging from the Earth’s depths are rich in iron, so they align with the planet’s geomagnetic field, “freezing” the strength and direction of the magnetic field in place by the time the lava cools to about 1,300 degrees Fahrenheit.
This rock sampling provided a picture of the Earth’s magnetic source over the past 160 million years. According to NASA, research shows that this field is the strongest in the last 100,000 years.
Don’t take magnetic orientation for granted
You can easily determine which direction the field is pointing using a compass. However, magnetic north has deviated from its normal position because where the liquid iron flows affects the location of the two magnetic poles. In fact, throughout the history of our planet, the poles have even changed their position several times, and the magnetic field strength has increased and decreased. Scientists recently noted that the recent shift of the magnetic north pole is occurring unusually quickly, ranging from a maximum of nine miles per year to as much as 37 miles per year between 1999 and 2005. This could have implications for any systems that require a compass, like your smartphone, or ships at sea.
Scientists believe that the Earth’s core began to solidify a billion years ago. However, traditional data shows that the magnetic Earth is more than three times older. It is now generally accepted that geomagnetism began 3.5 billion years ago, but paleomagnetists still don’t know how it happened.
Ancient rocks provide evidence of the existence of the Earth’s magnetic field
The rocks indicate that Earth had a strong magnetic field 3.7 billion years ago, but scientists are not sure where the field might have come from. Records of our planet’s ancient magnetism dating back 3.7 billion years have been discovered, proving that the Earth’s magnetic field existed very early in history. However, this discovery is quite surprising.
Rocks that are around 4 billion years old are hard to find; most were recycled by Earth’s tectonic activity, sliding into the mantle through subduction zones and then erupted back by volcanoes. Yet somehow, the rock sequence in the Isua supracrustal belt in Greenland has survived the ravages of time thanks to its unique geology, sitting on top of a thick continental plate, like a life raft amidst an ocean of tectonic upheaval.
Now researchers from the University of Oxford and the Massachusetts Institute of Technology have excavated some of these Isua stones and discovered that they contain iron records of the early Earth’s magnetic field. According to these data, our planet’s magnetic field does not seem to have changed much during this time, but geologists do not fully understand how the Earth could create a magnetic field at all then.
Claire Nichols
The existence of a magnetic field is critical to the development of life on Earth, and the field lines reflect the dangerous hail of charged particles blown toward us by the solar wind. Thus, the existence of an early magnetic field may have helped life gain a foothold on our planet.
Previous estimates and hints about the early Earth’s magnetic field have come from individual mineral crystals called zircons found in ancient rocks of Western Australia. This suggested the existence of a magnetic field 4.2 billion years ago. However, these results were subsequently questioned as unreliable.
The new results from Greenland rocks are considered more reliable because for the first time they rely on entire iron-bearing rocks (rather than individual mineral crystals) to determine the original field strength. The sample thus offers the first reliable measure of not only the strength of Earth’s ancient magnetic field, but also the time when the magnetic field originally appeared.
One of the 3.7 billion year old Greenland rocks that contains a relic of the Earth’s ancient magnetic field. Claire Nichols
“Extracting reliable records from such old rocks is extremely difficult, and it was really exciting to see primary magnetic signals begin to emerge as we analyzed these samples in the laboratory,” said lead researcher Claire Nichols, professor of planetary geology at the University of Oxford, in a statement to press. “This is a really important step forward as we try to determine the role of the ancient magnetic field when life first began on Earth.”
The iron particles in the Isua rocks can be thought of as tiny magnets, aligning with the Earth’s magnetic field when the rock around them first crystallized 3.7 billion years ago. Thus, their location holds the record for field strength. This force is estimated to have been at least 15 microtesla (mT), comparable to Earth’s field strength of 30 mT today.
However, this still leaves a mystery: how did the early Earth create its magnetic field?
Today, this field is created by a dynamo effect created by electrical currents in the Earth’s molten iron outer core, an effect caused by buoyancy forces as the planet’s inner core cools and solidifies. However, about a billion years ago, the inner core cooled enough that it began to solidify; 3.7 billion years ago it could not have affected the dynamo effect in the same way as it does today. In short, how the Earth’s ancient magnetic field came into being remains a mystery.
Fortunately, it was indeed created and undoubtedly helped primitive microbial life survive and thrive. In the past, the solar wind was stronger than it is today, but over time the Earth’s magnetic field would have been able to resist it, creating the conditions for life to escape from the oceans, where it was protected from harmful influences. radiation and on land.
Ancient bricks reveal changes in Earth’s magnetic field – iron oxide tells the whole story
Ancient bricks may hold the key to understanding Earth’s variable magnetic fields. Scientists examined the levels of iron oxide in 3,000-year-old bricks to understand the level of magnetism the bricks were exposed to during firing. This strategy could provide a new way to date ancient artifacts devoid of organic matter.
Ancient bricks appear to be able to tell the story of changes in the strength of the Earth’s magnetic field, opening up a new world of artifact dating.
A team of researchers, publishing their findings in the journal Proceedings of the National Academy of Sciences, showed how the ebb and flow of the Earth’s magnetic field left imprints on 3,000-year-old Mesopotamian clay bricks thanks to changes in iron oxide grains. Surprisingly, this data could mark the beginning of an entirely new method for dating ancient artifacts devoid of organic matter.
“We often rely on dating methods such as radiocarbon dates to gain insight into the chronology of ancient Mesopotamia,” Mark Altavil, co-author and professor of archeology at University College London, said in a statement. “However, some of the most common cultural remains, such as bricks and pottery, usually cannot be dated easily because they do not contain organic material. This work now helps provide an important dating framework that will allow others to benefit from absolute dating using archaeomagnetism.”
This new term, archaeomagnetism, refers to the signature of the Earth’s magnetic field in archaeological objects. This will not only help date artifacts, but will also tell experts more about the history of the Earth’s magnetic field, the strength of which changes over time.
It turns out that our planet’s magnetosphere leaves a distinct mark on minerals such as iron oxide as it heats up. So, when workers fired the clay bricks, they recorded evidence of the relative strength of the Earth’s magnetic field throughout time.
Determining the strength of a magnetic field on its own—without something to relate it to—can help us better understand the history of our planet, but it does little to help date the artifacts being studied. To do this, the team selected 32 bricks from archaeological sites throughout the region that was once Mesopotamia, each inscribed with the name of the reigning king.
“Accurately dated archaeological finds from rich Mesopotamian cultures, especially bricks inscribed with the names of specific kings, provide an unprecedented opportunity to study changes in field strength at high temporal resolution,” Lisa Tox, co-author and professor at the Institute of Oceanography. The study “tracks changes over several decades or less,” the statement said.
This is not an easy process. Iron oxide grain analysis involved examining tiny fragments of broken edges of bricks and using a magnetometer to accurately measure these remains.
“By comparing ancient artifacts with what we know about ancient magnetic field conditions,” Matthew Howland, lead author and professor at Wichita State University, said in a statement, “we can estimate the dates of any artifacts that were heated in ancient times.”
By matching the measured magnetic strength of the iron oxide grains with the person’s imprinted name and known reign, the team created a historical map of magnetic field shifts. This combination of science and history allowed specialists a unique look into the past – both of the object being analyzed and of our planet.
And it turns out that using timescales of the reigns of kings, some of whom reigned for only a few years, can provide an even narrower dating window than radiocarbon dating, which can often only reach a few hundred years.
This new ancient map also shows some unique events in the history of our planet. He was able to confirm an event known as the Levantine Iron Age geomagnetic anomaly, when the magnetic field was unusually strong from about 1050 to 550 BC. It also showed a dramatic change in the field over a relatively short period of time during the reign of Nebuchadnezzar II (604 to 562 BC), suggesting that rapid spikes in tension within our magnetic field can and do occur.
“This study,” the authors write in the study, “establishes the basis for the use of archaeomagnetic analysis as a method for absolute dating of archaeological materials from Mesopotamia.”
“Magnetized” boulders were discovered in one of the craters on the equator of the Moon
They influence the movements of lunar dust in the immediate vicinity of these boulders. European and Arab planetary scientists have discovered large boulders with unique magnetic properties in the lunar crater Rainer-K, which affect the movement of lunar dust in the immediate vicinity of these boulders. This was reported by the press service of the German University of Munster.
“We discovered these boulders immediately after we looked at the first photograph of this region of the Moon. They differ sharply from all other nearby cobblestones, since they scatter light much weaker than other nearby boulders. We assume that their unusual appearance is related to the way these stones interact with dust and the structure of the dust particles,” explained Ottaviano Ruesch, a researcher at the University of Münster, as quoted by the university’s press service.
Scientists made this discovery while studying high-quality images of the Ocean of Storms obtained using cameras from the LRO orbital probe. In these photographs, scientists looked for large lunar rocks that had been broken apart by heat and other natural factors. They are presumably fragments of ancient rocks of the lunar crust and mantle, which makes them interesting in the context of studying the history of the formation of the Moon.
Lunar crater Reiner-K
When scientists began looking for similar fractured rocks in the vicinity of the Rainer K crater, they discovered that a small but significant portion of the local boulders looked completely different from other similar-sized boulders on the surface of the Moon. At certain viewing angles, they appeared significantly darker than their neighbors, which was due to the fact that these boulders scattered sunlight in a unique way that is not characteristic of all other lunar rock fragments.
Subsequent examination of photographs of these fractured rocks revealed that these lunar boulders were covered with a thick layer of dust. The sizes of its particles, as well as their physical properties and location, are very different from the rest of the neighboring “dark” cobblestones. Subsequent calculations and observations indicated that these differences were due to the fact that these cobblestones have anomalous magnetic properties.
This is supported, in particular, by the fact that inside the Reiner-K crater and in its immediate vicinity there is one of the lunar magnetic anomalies, the nature of which scientists have been studying for quite a long time. Subsequent observations of this crater, as well as NASA’s planned dispatch of a lunar rover to this region of the Ocean of Storms, will help reveal the nature of the “magnetization” and other anomalous properties of these boulders, the researchers concluded.