Researchers Claim Earth's Inner Core Has Slowed down and Is Now Moving Backward

Earth's Core Motion Has Slowed Down

Earth's core has been a fascinating concept for experts all over the world. As per a recent study by the University of Southern California (USC), the core's motion has slowed down to such an extent that it is now spinning backward, CNN reported. Considering that the present equipment is incapable of reaching the solid metal ball which is the core inside the earth's surface, making assertions about them has been difficult for scientists. Most of the assertions about the structure's features have been made by scientists with the help of waves associated with it. The study also backs up the claim that this phenomenon of slow-spinning could have a hand behind the gradual shortening of the Earth's day.

Earth's Inner Core

The core is located 3,220 miles (5,180 kilometers) deep inside Earth. The structure is solid from the inside and liquid from the outside and protected by a solid rocky mantle. The inner core is made of iron and nickel and is estimated to be as hot as the surface of the sun — about 9,800 degrees Fahrenheit (5,400 degrees Celsius). The structure was first discovered by Danish seismologist, Inge Lehmann, in 1936. Since then, experts have dedicated days and nights to understanding its features. The core's spin is one topic that has garnered a lot of focus from experts. For decades scientists claimed that the inner core spun but it took them decades to have solid proof to back up this claim. "Differential rotation of the inner core was proposed as a phenomenon in the 1970s and ’80s, but it wasn’t until the ‘90s that seismological evidence was published," said Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia.

Analysis of Earth's Inner Core's Rotation

The experts from USC gained data for their analysis of the inner core from various earthquakes and nuclear tests, both of which send waves all across the planet, Space reported. The scientists considered the speed and interaction of the seismic waves within the Earth's layers to estimate the inner core's position and movement. The findings indicated to the experts, that since 2010 the Earth's inner core has been slowing down, or backtracking, compared to its speed in previous decades. The USC scientists also claimed in a statement that the inner core is even spinning slower in comparison to Earth's surface.

Inner Core's Slow Pace

Experts believe that the slow pace of Earth's inner core is because of the convection facilitating within the liquid iron outer core, which sustains Earth's magnetic field and the pull enjoyed by the gravitational forces present in the overlying mantle, Space reported. The experts focused on earthquakes that occurred around the South Sandwich Islands in the South Atlantic between 1991 and 2023 as well as core-penetrating shock waves from Soviet nuclear tests conducted between 1971 and 1974, to reach their conclusions. According to the scientists if the core spun at the same pace then identical seismographs would be produced over the years from the same location. They noted subtle changes in the time taken by the seismic waves to travel through the Earth throughout the years, in the South Sandwich Islands. The findings indicated, that the core is following a 70-year pattern when it comes to rotational speed. In the 1970s the inner core was spinning a little faster than the planet, by the time 2008 came around it had slowed down, and from 2008 to 2023 it began moving slightly in reverse, relative to the mantle.

Impact on Humans

Dr. John Vidale, Dean’s Professor of Earth Sciences at the University of Southern California’s Dornsife College of Letters, Arts and Sciences and the study's co-author, stated that the core's spin is imperceptible to people on Earth’s surface, CNN reported. He explained that the core's slowing down, speeds up the mantle, making the Earth rotate faster. The alteration in Earth's rotation shortens the day, but the difference is so minuscule that people would barely notice it, as per experts. "In terms of that effect in a person’s lifetime?" Vidale said. "I can’t imagine it means much." Vidale hopes that similar studies in the future are done to explore the earth's inner core. According to Vidale and his co-authors, humans must continue to enhance their knowledge about the inner core to understand the structure's precise role in the planet's magnetic field.