Earth’s magnetic field has been a life preserver, protecting against relentless solar winds, streams of charged particles rushing from the Sun, that otherwise could strip away the planet’s atmosphere and water.
‘It would be a pretty barren planet without it,’ said University of Rochester geophysicist John Tarduno.
But there has been debate among scientists about when this vital shield generated by Earth’s liquid iron core formed.
Researchers said evidence entombed in tiny crystals retrieved from the outback of western Australia indicates the magnetic field arose at least 4.2 billion years ago, much earlier than previously believed.
Previous research had estimated the field originated about 3.5 billion years ago, roughly a billion years after Earth’s formation.
The new study shows Earth was protected by its magnetic field beginning very early in its history.
‘The solar wind would have been much more intense 4 billion years ago,’ said Tarduno, who led the study published in the journal Science.
‘Its erosional capability was perhaps 10 times greater than it is today. Without a magnetic shield, you would have this tremendous possibility of eroding the atmosphere and removing water from the planet.’
WHAT COULD HAPPEN IF OUR MAGNETOSPHERE CONTINUES TO WEAKEN?
The magnetosphere protects the Earth from solar radiation.
If it weakens dramatically, radiation at ground level would increase with some estimates suggesting that overall exposure to cosmic radiation would double causing more deaths from cancer.
The Electric grid collapse from severe solar storms is a major risk.
As the magnetic field continues to weaken, scientists are highlighting the importance off-the grid energy systems using renewable energy sources to protect the Earth against a black out.
‘The very highly charged particles can have a deleterious effect on the satellites and astronauts,’ added Dr Mona Kessel, a Magnetosphere discipline scientist at Nasa.
Earth’s protective shield is slowly weakening, allowing harmful solar winds to penetrate the atmosphere
The Earth’s climate could also change. A recent Danish study has found that the earth’s weather has been significantly affected by the planet’s magnetic field.
They claimed that fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.
A weakened magnetosphere will also mean that more aurora will be seen on Earth as solar winds hit the atmosphere.
The study focused on a mineral called magnetite contained inside ancient zircon crystals from Australia’s Jack Hills.
Magnetite preserves a record of magnetic field strength at the time the mineral was trapped in the zircon.
The researchers examined magnetite in zircon crystals measuring about one-tenth to two-tenths of a millimeter in size and dating from about 3.2 billion to 4.2 billion years ago, and concluded Earth possessed a magnetic field during that entire period.
Without a magnetic field, it may have been difficult for life to emerge on Earth as it has.
‘Knowing the initiation of the magnetic field has implications for habitability conditions of early Earth,’ said University of Rochester geologist Rory Cottrell.
‘Finding suitable geologic material to measure deep time is a challenge in and of itself. Zircon grains from Western Australia may be one way to obtain such information about the early magnetic field,’ Cottrell added.
The layers of Earth’s upper atmosphere, the ionosphere, and magnetosphere, form a closely-paired, interacting system. Swarm is contributing to a better understanding of near-Earth electric current systems and processes as shown in this graphic
Only two of the solar system’s rocky planets, Earth and Mercury, possess a magnetic field. Mars previously had one, but it dissipated about 4 billion years ago.
‘Mars once had a much denser atmosphere and oceans,’ said Tarduno.
The magnetic field’s disappearance exposed Mars to solar winds that may have peeled off the atmosphere and water, leaving the planet desolate.
Earth’s protective shield is slowly weakening, allowing harmful solar winds to penetrate the planet’s atmosphere.
Known as the magnetosphere, this shield extends thousands of miles into space and affects everything from global communication to weather patterns.
The European Space Agency’s Swarm mission aims to map changes to magnetosphere – and, after a year in orbit, it’s now provided a glimpse into its dynamics.
The initial results from Swarm are due to be presented at the General Assembly of the International Union of Geodesy and Geophysics on 22 June to 2 July in Prague, Czech Republic.
Rune Floberghagen, Swarm Mission Manager, said, ‘These results show that all the meticulous effort that went into making Swarm the best-ever spaceborne magnetometry mission is certainly paying off.’
Swarm is tasked with measuring and untangling the different magnetic signals that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere.
The four-year mission is hoping to eventually provide an insight into various natural processes, from those occurring deep inside the planet through to weather in space caused by solar activity.
The three satellites are identical, but to optimise sampling in space and time their orbits are different and change over the course of the mission’s life.
Swarm is the first mission to take advantage of something known as ‘magnetic gradiometry’, which is achieved by two of the satellites orbiting side-by-side at a distance of about 60 miles (100km).
A weakened magnetosphere means that more aurora will be seen on Earth as solar winds hit the atmosphere
This is used to unravel the details of the magnetic field produced by magnetised rocks in Earth’s crust.
Nils Olsen from DTU Space in Denmark said: ‘We are extremely satisfied with these preliminary results.
‘Not only do they validate the gradiometry concept, but they also confirm the remarkable accuracy of the satellites’ absolute magnetic measurements.’
The Swarm constellation also makes it much easier to monitor the changes that occur in the main field produced in the Earth’s core, which protects us from harmful charged cosmic particles.
‘Our magnetic field is largely generated by Earth’s outer core,’ said Gauthier Hulot, one of the lead proposers of the Swarm mission.
‘The constellation provides detail on the way the field is changing and thereby weakening our protective shield.’
‘This is what will ultimately make it possible to predict the way this field will evolve over the next decades.’
The Swarm satellites will be in orbit for another three years at least.
These results will be presented at the 26th General Assembly of the International Union of Geodesy and Geophysics on 22 June to 2 July in Prague, Czech Republic.
Courtesy of dailymail.co.uk