Scientists have detected a rhythmic 'heartbeat' emanating from the center of the Earth.

While it's not large enough to be felt like an earthquake, it's noticeable enough for seismologists worldwide to pick up a small, measurable 'blip' on their instruments. Geologists have dubbed this pulse a 'microseism,' first observed originating from the ocean and occurring approximately every 26 seconds.

This rhythmic pulse has been quietly pulsing for decades, yet scientists remain unsure about its exact cause.

Jack Oliver, a researcher at the Lamont-Doherty Geological Observatory, was the first to document the pulse in the 1960s. While studying seismic activity, he traced it back to somewhere 'in the southern or equatorial Atlantic Ocean.' According to Oliver, the pulse was stronger during the Northern Hemisphere’s summer months (or the Southern Hemisphere’s winter). This was a time when technology was far less advanced.

“Jack didn’t have the tools in 1962 that we had in 2005 — he didn’t have digital seismometers, and was working with paper records,” said Mike Ritzwoller, a seismologist at the University of Colorado. Ritzwoller’s team would later encounter the same mysterious pulse.

In 1980, Gary Holcomb, a geologist with the U.S. Geological Survey, contributed further insights when he discovered that the pulse was most prominent during storms.

In 2005, Greg Bensen, a graduate student at the University of Colorado Boulder, was reviewing seismic data when his advisor asked to see what he was working on. Ritzwoller recalled that Bensen pulled up the data, and there it was—the repeating, distant blip. “As soon as we saw this, [postdoctoral researcher Nikolai Shapiro] and I recognized something unusual, though we had no idea what it was,” Ritzwoller added.

The team analyzed the pulse from all possible angles and traced its source to the Gulf of Guinea, off the coast of West Africa. They published their findings in 2006, but even today, no one can explain the steady rhythm. Some experts suggest it could be related to waves crashing on the seafloor, while others consider volcanic activity as a possible cause. However, one thing is certain: our planet is constantly making some form of noise.

“Seismic noise exists because of the Sun,” said Ritzwoller. The Sun heats the Earth unevenly, warming the equator more than the poles. This imbalance drives winds, ocean currents, and waves that can create land vibrations when they crash into coastlines.

Scientists have found that this 'seismic noise' can be used to study Earth's interior. “But the discovery of [this pulse in 2005] was a complete surprise,” Ritzwoller continued.

“We’re still waiting for a fundamental explanation of this phenomenon.”

He concluded: “The key takeaway is that there are fascinating, fundamental phenomena within the Earth that are known to exist but remain a mystery. It may take future generations to fully uncover the truth.”