Earth’s Most Remote Spot Hears Mystifying Ultra-Low-Frequency 'Bloop' Sound

In 1997, the U.S. National Oceanic and Atmospheric Administration (NOAA) underwater microphones picked up a strange, intense sound from over 5,000 kilometers away. The sound was traced to a remote spot called Point Nemo in the South Pacific Ocean, near the southern tip of South America. This area was the most isolated place on Earth, about 1,671 miles from the nearest land. Scientists were baffled by its origins and what could have caused it.

Al Kogut, the ARCADE team head at NASA's Goddard Space Flight Center in Greenbelt, Maryland, explained to Space.com , "It was a diffuse signal coming from all directions, so it was not caused by any one single object. The signal also had a frequency spectrum, or 'color,' that was similar to radio emission from our own Milky Way galaxy."

NASA's ARCADE instrument was designed to study the cosmic microwave background and other space phenomena. Knewz.com learned that it floated about 23 miles (37 kilometers) above Earth to avoid disturbances and scanned the night sky for radio signals. The data collected by ARCADE stunned scientists as it differed completely from their predictions. This 'space roar' might have been coming from something new and unknown in the universe.

NOAA oceanographer Chris Fox told CNN , "There were a lot of things making noise down there, including whales, dolphins, fish, and the rumblings of the Earth." He added, "I thought it might be related to ice calving. It always came from the south. We suspected that it was ice off the coast of Antarctica, in which case it was incredibly loud."

Scientists explored various theories about the signal’s origin. Some believed it might have been from distant galaxies, while others suggested it could be linked to dark matter or the first stars. Many thought it could be a new type of emission we hadn’t discovered yet. NASA scientist Dale J. Fixsen explained, "In other spiral galaxies, there was a close relation between infrared and radio emission, even in small sections. So, if it was from a halo around our galaxy, it would have made the Milky Way a weird galaxy, while in most other respects, it seemed like a 'normal' spiral galaxy."

According to the Pacific Marine Environmental Laboratory, as reported by TwistedSifter , "The broad spectrum sounds recorded in the summer of 1997 were consistent with icequakes generated by large icebergs as they cracked and fractured."

Jack Singal, an assistant professor of physics at the University of Richmond in Virginia, mentioned that mistakes in ARCADE's data and other measurements might have been a possibility. To solve this mystery, scientists considered sending ARCADE back up with new technology for better sensitivity, which could have been useful.

Singal also shared, "With some collaborators, I attempted to use the Low-Frequency Array (LOFAR) in The Netherlands. Both of these measurements together could help determine whether the radio synchrotron background was primarily galactic or extragalactic in origin. Beyond that, we might have needed a brilliant new hypothesis that no one had thought of yet."