Is there something strange and alien deep within the Earth? Is he trying to break free and escape to heaven? No, of course not. But it sure sounds like it in ESA’s new audio environment. Approximately every 450,000 years, Earth’s magnetic poles switch places. In a phenomenon called geomagnetic field inversion, north becomes south and vice versa. The discovery was shocking because the planet’s magnetic field is such a fundamental part of our environment. However, these changes are mostly harmless to life.
Geomagnetic reversals are chaotic events. Although they appear on average every 450,000 years, they are not regular. There have been approximately 183 years in the last 83 million years, which brings us to a total of 450,000 years. But the last one was 780,000 years ago, and some say we’re overdue for the next one.
Sometimes events are excursions rather than full U-turns. This is when the field changes over several hundred years before returning to its original orientation, as in the Laschamps event about 41,000 years ago. During the trip, the field in the Earth’s outer core changes, while its inner core remains unchanged. These occur more frequently than complete cancellations, but their exact number and timing are more difficult to determine because their effects are not global.
Evidence of these reversals and deviations is found in paleomagnetism. Paleomagnetism measures the orientation of magnetic elements, such as iron, during the cooling of volcanic rock. By determining the age of the rock, scientists can determine the direction of the Earth’s magnetic field when the rock solidified. The history of changes in the Earth’s magnetic field is recorded where new magma cools as the seafloor spreads.
During these trips and returns, the strength of the magnetic field weakens. During the Laschamp event, which lasted several hundred years, the field weakened to only 5% of its normal strength.
Earth’s magnetic fields redirect cosmic rays away from Earth, and the field at only 5% of its normal strength allows many more cosmic rays to pass through than normal. Cosmic rays are high-energy particles, typically protons or atomic nuclei, that are emitted from the sun and objects in and outside the Milky Way and move at relativistic speeds. When they enter the Earth’s atmosphere, they create showers of secondary particles.
Regardless of how often they happen or what causes them, scientists are pretty sure the Laschamps event was the last trip, and the European Space Agency decided it would be good for us to know what it looked like.
ESA launched the three-satellite Swarm mission in 2013 to study Earth’s magnetic fields. Swarm measures magnetic signals extending not only from the core but also from the mantle, oceans, and into 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 the soundscape of the Laschamps event.
Scientists used recordings of natural sounds, such as falling rocks and creaking wood, and mixed them with alien-like sounds, both familiar and unfamiliar. The result feels earthy, subterranean, natural, and spooky at the same time, as if an ancient part of the Earth were floating around the planet, which in a way it is. The first version was created in 2022 and exhibited as a type of public art installation in Copenhagen. There were 32 speakers, each reproducing the sound represented by changes in the magnetic field at 32 points on the earth.
Source: Port Altele
