Chinese astronomers remain puzzled over a strange signal that was picked up by one of the world’s most powerful radio telescopes. The rare phenomenon cannot be explained and scientists say they don’t want to jump to conclusions.

China’s Five-hundred-meter Aperture Spherical Radio Telescope (FAST) has detected a repeating fast radio burst (FRB) – unexplained radio signals coming from outer space – for the first time last week, according to reports.

First discovered in 2007, FRBs are extremely rare, with fewer than 100 having been documented to date.

FRBs usually only appear once, making them extremely difficult to track. Curiously, the FRB detected by the Chinese telescope has been observed before.

Known as FRB121102, the radio signal was first discovered in 2012 and later repeated in 2015. The signal came from a dwarf galaxy located three billion light years from Earth.

Between August 30 and September 3, FAST recorded dozens of pulses from the FRB.

While undoubtedly exciting, not enough is known about the enigmatic signal to draw any conclusions about what could have created it, according to Zhang Xinxin, an assistant engineer with the National Astronomical Observatories of China.

Some theories have already been ruled out, though. The astronomers say that they are certain that the signal is not the result of interference from aircraft or satellites. The scientific community remains baffled by FRBs and where they come from.