Mysterious radio wave pulses from deep in space have been hitting Earth for decades, but the scientists who recently discovered them have no concrete explanation for the origin of the signals.

For 35 years, the strange blasts of energy in varying levels of brightness have occurred like clockwork approximately every 20 minutes, sometimes lasting for five minute intervals. That’s what Curtin University astronomers from the International Centre for Radio Astronomy Research (ICRAR) concluded in research published last week in the journal Nature.

The discovery of the signal, which researchers named GPMJ1839-10, has the scientists baffled. Believed to be coming from around 15,000 light years away from Earth, the signal has been occurring at intervals and for a period of time previously thought to be impossible.

“This remarkable object challenges our understanding of neutron stars and magnetars, which are some of the most exotic and extreme objects in the universe,” lead author Dr. Natasha Hurley-Walker said in a statement on ICRAR’s website.

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First signal detected from 2018 data

Using data gathered in 2018, astronomers first detected another magnetar spinning much slower than usual and sending similar signals every 18 minutes. But by the time they analyzed the data in 2020, it was no longer producing radio waves, according to Hurley-Walker.

So they looked again, knowing that the chance was high they would find another long-term radio source.

The team of astronomers used the Murchison Widefield Array radio telescope in Western Australia to scan the Milky Way galaxy every three nights for several months. They didn’t have to wait long to find what they were looking for.

Within no time, a new source was discovered in a different part of the sky, this time repeating every 22 minutes with five-minute pulses.

Studying records at the Very Large Array in New Mexico, which maintains the longest-running archive of data, the researchers discovered that the source’s pulse was first observed in 1988.

What’s even more alarming than that this radio signal was able to go undetected for more than three decades is that scientists have not determined with confidence what it could be.