LISTEN: Mysterious 'alien call' comes from 36,000 ft below the Earth's surface

Mariana Trench via Google Maps

What is the sound that has scientists spooked? It was recorded coming from the deepest part of the ocean and researchers at Oregon State University were stunned when they heard it.

The researchers at the Hartfield Marine Science Center were monitoring deep-sea whale communications in the Pacific Ocean's Mariana Trench when they were heard the wailing noise. LISTEN to the chilling sound here.

The experts' best guess is that they picked up a never-before-heard whale call from a baleen whale.

“It’s very distinct, with all these crazy parts,” said Sharon Nieukirk, senior faculty research assistant in marine bioacoustics at Oregon State. “The low-frequency moaning part is typical of baleen whales, and it’s that kind of twangy sound that makes it really unique. We don’t find many new baleen whale calls.”

Marine experts sent passive acoustic ocean gliders to the bottom of the Mariana Trench. The instruments travel autonomously for months at a time and can dive up to 3,281 feet.

The Mariana Trench is the deepest known part of the Earth's oceans and has depths in excess of 36,000 feet. For comparison, the world's tallest building - the Burj Khalifa - is only 2,722 feet.

From just 3,281 feet under the surface, the technology picked up the strange booming sound.

While it's believed to be a mating call from baleen whale, it's not confirmed. This is because the bizarre sound pattern doesn't fit with what scientists already understand about whales.

“If it’s a mating call, why are we getting it year round? That’s a mystery,” said Nieukirk

The team hopes that by publishing the brief sound, other researchers can help identify it in past and future data.

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