Scientists in Puerto Rico have detected mysterious radio signals from a star 11 light years from Earth earlier this month.
Scientists say the pulses from the star, known as Ross 128, are "very peculiar" compared to those of similar nearby stars.
Researchers at the Arecibo Observatory in Puerto Rico discovered the signals as they observed a group of red dwarf stars.
Abel Méndez, director of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, said the origin of the signals is still unknown, but they're not coming from aliens.
Méndez, who has been working in astrobiology for more than 20 years, says this doesn't happen often.
"We can't tell apart at this moment if the signal is astronomical or terrestrial in nature, that's the mystery. Our priority is to know its source first. Then, we will try to understand why the source is emitting such signals," he told Circa.
Méndez said he is expecting an update on the signal results later this week.
"I received other suggestions by fellow astronomers on probable stellar phenomena that might explain the signals, such as radio signals from coronal mass ejections," he said. "But those are one of many possibilities."
Others aren't so sure aliens aren't involved.