The study indicates that the innermost layer of the Earth is a ball of iron 400 miles wide

(CNN) Scientists have long wondered what lies at the center of the Earth, and the latest research puts weight behind the theory that our planet contains a distinct ball of iron inside its metallic core.

Beneath the outer crust, the mantle f molten liquid outer core It’s the center of Earth’s solid mineral — which actually contains a hidden layer, or “deeper inner core,” according to a new study published Tuesday in the journal Nature. Nature Communications.

The huge discovery indicates that Earth has five main layers instead of four, and provided new details that scientists can use to help unlock some of the oldest mysteries about our planet and how it was formed.

Geologists first suggested that Earth’s core might contain an extra, imperceptible layer about 20 years ago, according to a press release. Now, using new datasets collected by measuring seismic waves of earthquakes as they pass through the center of the Earth, researchers have finally discovered that innermost core, the new study said.

seismic waves They are vibrations that occur within or along the Earth’s surface and through its inner layers as a result of earthquakes, volcanoes, or other means.

“In this study, for the first time, we report observations of seismic waves originating from strong earthquakes that travel back and forth from one side of the globe to the other up to five times as recoil,” said study co-author Dr. Thanh Son Phum. , a seismologist and postdoctoral fellow in the School of Geosciences Research at the Australian National University in Canberra, in an email.

Detection through earthquake activity

Pham said the reason this layer wasn’t previously observed in more detail is because its composition is very similar to what lies above it. Both the newly discovered cores — which the study indicates are likely to be a 400-mile (644-kilometer) wide sphere of metal whose outer shell is made of iron-nickel alloys, with trace amounts of other elements.

“In addition, the transition from the innermost (solid) sphere to the outer shell of the inner core (also the hard shell) seems more gradual than sharp,” said Pham. “That’s why we can’t detect it by direct reflections of seismic waves from it.”

Using instruments that detect vibrational waves, the researchers found that the innermost, inner core has characteristic anisotropy, a property of a material that allows it to take on different properties depending on the angle at which it is approached. An example of an anisotropic object is a piece of wood: it is much easier to break through a piece of wood by striking it in the direction of its direction than against it.

This is the feature that characterizes the innermost essence.

When it came to assessing the Earth’s core, the researchers looked at how fast seismic waves They traveled through it in different directions, and found that the innermost inner core changes the speed of those waves in a different way than the layer above it, the outermost shell of the central core.

Spotting the new layer more than 1,000 miles (1,600 kilometers) below our feet is significant. The existence of a distinct deeper core could give scientists a better understanding of Earth’s magnetic field and how it has evolved and will continue to do so.

The new discovery It also “gives us a glimpse of what might be going on with other planets,” Pham said. “Take Mars as an example. We don’t yet understand why (the magnetic field of Mars) no longer existed in the past.”