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Aug 1 15 1:55 PM
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] Satellite Swarm Spots North Pole Drift 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. VIDEO: What Will Happen When The North And South Poles Flip? "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."
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]
Satellite Swarm Spots North Pole Drift
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.
VIDEO: What Will Happen When The North And South Poles Flip?
"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."
Earth's magnetic field is 800 million years older than previously thought, new research suggests. A new analysis of Western Australian zircon minerals has found the engine that generates the field started not long after the planet formed. Earth's so-called "geodynamo", involving the movement of molten iron in the Earth's outer core, began 4.22 billion years ago, say researchers today in the journal Science. "This opens a window into a period that we know almost nothing about," says co-author, Professor Francis Nimmo of the University of California, Santa Cruz. "Before this study we knew that the dynamo had existed for around three and a half billion years. What this study has done is push back the age of the dynamo by another 800 million years." Earth's magnetic field acts as a shield protecting the planet's atmosphere and water, which make life on Earth possible. Without the magnetic field Earth's atmosphere would have been eroded away by the solar wind, a stream of charged particles flowing from the Sun. The magnetic field was particularly important in Earth's early history when solar winds were about 100 times stronger than they are now. "The young Sun was very active, and so having a strong magnetic field early on allows you to hang on to your atmosphere," says Nimmo. "Mars had a dynamo early on, but then that dynamo died," he says. "So part of the reason that Mars lost its atmosphere is not simply that it has less gravity, but also that it didn't have a magnetic field protecting the atmosphere from being blown away."Zircon crystalsIn their new study Nimmo and colleagues calculated when Earth's geodynamo started by analysing zircon crystals from Jack Hills in Western Australia. "Jack Hills zircons are famous because they are the oldest minerals we know of on this planet," says Nimmo. The zircons, which are billions of years old, contain a naturally occurring magnetic iron oxide (magnetite), which records the strength of the magnetic field at the time it solidified from its molten state. The researchers used a unique magnetometer to measure the magnetic intensity of the magnetite in zircons of different ages, to probe the history of the planet's magnetic field.
Earth's magnetic field is 800 million years older than previously thought, new research suggests.
A new analysis of Western Australian zircon minerals has found the engine that generates the field started not long after the planet formed.
Earth's so-called "geodynamo", involving the movement of molten iron in the Earth's outer core, began 4.22 billion years ago, say researchers today in the journal Science.
"This opens a window into a period that we know almost nothing about," says co-author, Professor Francis Nimmo of the University of California, Santa Cruz.
"Before this study we knew that the dynamo had existed for around three and a half billion years. What this study has done is push back the age of the dynamo by another 800 million years."
Earth's magnetic field acts as a shield protecting the planet's atmosphere and water, which make life on Earth possible.
Without the magnetic field Earth's atmosphere would have been eroded away by the solar wind, a stream of charged particles flowing from the Sun.
The magnetic field was particularly important in Earth's early history when solar winds were about 100 times stronger than they are now.
"The young Sun was very active, and so having a strong magnetic field early on allows you to hang on to your atmosphere," says Nimmo.
"Mars had a dynamo early on, but then that dynamo died," he says.
"So part of the reason that Mars lost its atmosphere is not simply that it has less gravity, but also that it didn't have a magnetic field protecting the atmosphere from being blown away."
In their new study Nimmo and colleagues calculated when Earth's geodynamo started by analysing zircon crystals from Jack Hills in Western Australia.
"Jack Hills zircons are famous because they are the oldest minerals we know of on this planet," says Nimmo.
The zircons, which are billions of years old, contain a naturally occurring magnetic iron oxide (magnetite), which records the strength of the magnetic field at the time it solidified from its molten state.
The researchers used a unique magnetometer to measure the magnetic intensity of the magnetite in zircons of different ages, to probe the history of the planet's magnetic field.
Read more @ http://www.abc.net.au/science/articles/2015/07/31/4283843.htm
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