Astronomers have discovered a repeating Fast Radio Burst (FRB)

(Animation of FRBs over the observable detection range. Credit: NRAO Outreach/T. Jarrett (IPAC/Caltech); B. Saxton, NRAO/AUI/NS)

Fast Radio Bursts or FRBs are repeating natural (or unnatural) signals and what appeared from these bursts of, what was thought was random, radio light when they were first detected in 2007.  Have now shown recently that they have a repeating overlapping signal, in this case, from the same source.  This is the second time so far in the short history of discovering FRBs have revealed a repeated pattern.

Of course Aliens are last in the list, but the mystery of theses pulses have shown that if they reflect  a pattern sequence thus may also indicate that the unnatural possibility (Extraterrestrial Intelligence) could be an answer.

From Live Science:

"...The mystery is partially owed to a lack of data; since astronomers first discovered FRBs in 2007, only about 60 have been observed. Now, those numbers are growing fast. According to two new papers published today (Jan. 9) in the journal Nature, scientists working at the CHIME (Canadian Hydrogen Intensity Mapping Experiment) radio telescope in the hills of British Columbia have detected 13 new FRBs in just a two-month span. Among these newly captured signals are seven bursts that registered at 400 megahertz — the lowest FRB frequency detected so far — and, for only the second time ever, an FRB that flashed repeatedly, six times in a row. [Stephen Hawking's Most Far-Out Ideas About Black Holes] "Until now, there was only one known repeating FRB," Ingrid Stairs, a member of the CHIME team and an astrophysicist at the University of British Columbia, said in a statement. "With more repeaters and more sources available for study, we may be able to understand these cosmic puzzles — where they're from and what causes them..."

and

"...Moreover, the CHIME team's new discoveries suggest that FRBs are probably far more common than current technology is able to reflect. The fact that seven of the new bursts registered at 400 MHz (the lowest frequency the CHIME telescope is able to detect) suggest that FRBs with even lower frequencies are likely zipping past our planet all the time — we just aren't able to see them yet."