THERE’s a growing gap in the Earth’s defences.
We’ve known for more than a century that our planet’s magnetic field has been weakening.
It’s what gives us our north and south poles.
This powers our compasses.
It’s also a vital shield that protects us from harmful radiation constantly bombarding us from the Sun or deep space.
This weakening is most evident in one place. It’s a hole that reaches across the heart of South America, over the South Atlantic and into Africa.
It’s been dubbed the “South Atlantic Anomaly”.
It’s allowing more high-energy radiation to penetrate deeper through near orbit, the atmosphere and to our surface.
In recent decades it’s caused computers to crash on Shuttles and the International Space Station.
In 2016, Japan’s revolutionary Hitomi X-ray observation satellite that was supposed to study black holes and supernovas was struck while passing through the gap and sent spinning out of control.
A new study, published in the science journal Geophysical Research Letters, has been digging back in time to find out just how long this anomaly has been active in the area — and what it may mean for our future.
“We’ve known for quite some time that the magnetic field has been changing, but we didn’t really know if this was unusual for this region on a longer timescale, or whether it was normal,” says University of Rochester physicist Dr Vincent Hare.
The burnt-clay huts reveal similar dips in the magnetic field happened around 400-450 BC, 700-750 BC, and 1225-1550 BC. This mean’s the current weakening has been developing for some time.
“We’re getting stronger evidence that there’s something unusual about the core-mantel boundary under Africa that could be having an important impact on the global magnetic field,” Professor Tarduno says.
“We now know this unusual behaviour has occurred at least a couple of times before the past 160 years, and is part of a bigger long-term pattern,” Dr Hare says.
“However, it’s simply too early to say for certain whenews.com.au
