Is there something strange and alien trapped deep within the Earth? Is it trying to break free and escape to heaven? No, of course not.
But in a new soundscape from ESA, it certainly sounds like it.
The Earth's magnetic poles reverse approximately every 450,000 years. The north becomes the south and vice versa in a phenomenon called geomagnetic reversal. This discovery was shocking because the planet's magnetic field is such a fundamental part of our environment. However, these reversals appear to be mostly harmless to life.
Geomagnetic reversals are chaotic events. Although they occur on average about every 450,000 years, there is no pattern to them. There have been about 183 of them in the last 83 million years, which brings us to a figure of 450,000 years. But the last one was 780,000 years ago and some say the next one is long overdue.
Sometimes the events are more of swings than complete reversals. The field shifts for several hundred years and then returns to its original orientation, as in the Laschamps event around 41,000 years ago. During an excursion, the field in the Earth's outer core reverses, while the inner core remains unchanged. These occur more frequently than full reversals, but their exact number and timing are more difficult to determine because their impact is not global.
Evidence for these reversals and deviations can be found in paleomagnetism. Paleomagnetism measures the orientation of magnetic elements, such as iron, in volcanic rocks as they cool. By determining the age of rocks, scientists can determine the orientation of the Earth's magnetic field when the rock solidified. The history of Earth's magnetic reversals is recorded where new magma cools as the ocean floor spreads.
Magnetic stripes are the result of reversals in the Earth's field and seafloor spreading. The new oceanic crust is magnetized as it forms and then moves away from the ridge in both directions. This diagram shows a mountain ridge (a) about 5 million years ago, (b) about 2 million years ago, and (c) in the present. Image source: From Chmee2 – derived from File:Oceanic.Stripe.Magnetic.Anomalies.Scheme.gif, Public Domain, https://commons.wikimedia.org/w/index.php?curid=18557170
During these deflections and reversals, the strength of the magnetic field weakens. During the Laschamps event, which lasted several hundred years, the field weakened to just 5% of its normal strength.
Earth's magnetic fields deflect cosmic rays away from the Earth, and at just 5% of their normal strength, the field allows far more cosmic rays to pass through than usual. Cosmic rays are high-energy particles, usually protons or atomic nuclei, that emanate from the Sun and objects inside and outside the Milky Way and travel at relativistic speeds. When they hit the Earth's atmosphere, they produce showers of secondary particles.
Regardless of how often they occur or what causes them, scientists are pretty sure that the Laschamps event was the most recent excursion, and the European Space Agency decided it would be good if we knew what it sounded like.
ESA launched its three-satellite Swarm mission in 2013 to study Earth's magnetic fields. Swarm measures magnetic signals not only from the core, but also from the mantle, the oceans and up to the ionosphere and magnetosphere. Scientists from the Technical University of Denmark and the German Research Center for Geosciences used swarm data and data from other sources to create a soundscape of the Laschamps event.
The scientists used recordings of natural sounds, such as falling rocks and the creaking of wood, and mixed them together to create alien sounds that were both familiar and strange. The result sounds terrestrial, subterranean, natural and creepy at the same time, as if an ancient part of the earth were twisting inside the planet, which in a way it is.
The first version was created in 2022 and was played as a kind of public art installation in Copenhagen. There were 32 speakers, and each of them played the sound represented by changes in the magnetic field in 32 locations around the world.
Check out ESA's SoundCloud channel where they publish their audio creations.
Like this:
Load…
Comments are closed.