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According to a recently uploaded and then removed paper by Chinese scientists, China's massive "Sky Eye" observatory may have picked up trace signals from a distant extraterrestrial civilisation.

According to a report published Tuesday (June 14) in Science and Technology Daily, the official newspaper of China's Ministry of Science and Technology, astronomers at Beijing Normal University have discovered "several cases of possible technological traces and extraterrestrial civilizations from outside the Earth."

The signals were detected by China's FAST (Five-hundred-meter Aperture Spherical Radio Telescope), also known as "Sky Eye," the world's biggest radio telescope.

In 2019, Sky Eye was tasked with searching deep space for radio signals that may reveal extraterrestrial life; when the data was analyzed in 2020, the researchers discovered two suspicious narrow-band, presumably artificial radio emissions.

In 2022, another odd narrow-band radio signal was discovered in a focused study of known exoplanets, increasing the total to three. The signals might have been created by alien technology, as they are narrow-band radio waves that are generally exclusively utilized by human aircraft and satellites. The experts stress that their findings are preliminary and should be used with care until the investigation is complete.

"These are several narrow-band electromagnetic signals different from the past, and the team is currently working on further investigation," Zhang Tongjie, chief scientist of Beijing Normal University's China Extraterrestrial Civilization Research Group, told Science and Technology Daily.

"The possibility that the suspicious signal is some kind of radio interference is also very high, and it needs to be further confirmed and ruled out. This may be a long process."

Following its release, the report went viral on Weibo, China's social media platform, and was taken up by a number of other state-run media sources. It's unknown why it was removed so suddenly.

The signals aren't the first time that radio waves from outer space have perplexed scientists.

In August 1977, the Ohio State University's Big Ear telescope detected an unusually intense, minute-long electromagnetic burst that blazed at a frequency scientists hypothesized may be utilized by alien civilizations during a SETI (Search for Extraterrestrial Intelligence) search.

Jerry Ehman, a physicist working with the telescope that night, quickly scrawled "Wow!" in red ink on the sheet after noticing the signal on a data printout, giving the finding its famous moniker.

Follow-up searches in the same region of space have all come up empty-handed, and additional study has suggested that the signal might have originated from a Sun-like star in the constellation Sagittarius, as previously reported by Live Science. Despite this, the signal's origin remains a mystery.

Radio interference has famously stymied alien-hunting scientists in the past, so Chinese astronomers are eager to rule it out. Astronomers discovered a signal from Proxima Centauri, the closest star system to our sun (about 4.2 light-years distant) and home to at least one possibly habitable planet, in 2019.

Because the transmission was a narrow-band radio wave generally associated with human-made devices, experts speculated that it may have come from alien technology.

New research published two years later, however, revealed that the signal was most likely caused by faulty human technology, as previously reported by Live Science.

Similarly, between 2011 and 2014, another renowned set of signals thought to have come from aliens were discovered to be created by scientists microwaving their meals.

Tonjie went on to say that his team intends to repeat their observations of the odd signals in order to rule out radio interference and gather as much information as possible.

"We look forward to the [FAST telescope] being the first to discover and confirm the existence of extraterrestrial civilizations," Tongjie says.

The Fermi Paradox — a contradiction between the Universe's scope and age and the apparent lack of intelligent life forms beyond Earth – has long perplexed scientists.

The paradox gets its name from Nobel Laureate and physicist Enrico Fermi's informal lunchtime reflections, in which he is claimed to have quipped, "So where is everybody?" after considering the issue.