The "alien" signal that raised hopes of finding extraterrestrial civilization has been signed off as noise of earthly origin.
The signal was detected last year but gained attention this month after it was mentioned in a scientific presentation. Its apparent origins from a distant solar system a few billion years older than ours had sparked curiosity, raising hopes of an alien find.
The system HD 164595 in Hercules constellation about 95 light years away, houses a star comparable in size with the Sun and one known Neptune-sized planet in a tight orbit around the star. While the "alien" signal caught the media's fancy, scientists remained skeptical.
"There are many other plausible explanations for this claimed transmission - including terrestrial interference. Without a confirmation of this signal, we can only say that it's 'interesting'," SETI astronomer Seth Shostak wrote.
The signal was detected by Russia's RATAN-600 radio telescope in May 2015 but went largely unreported then. SETI suspects astronomers who spotted it did not report it for further analysis as they did not believe it was extraterrestrial.
Shostak had explained the signal was weak and would have required more than trillion watts of energy to beam at earth. Though the beam's highly elongated shape sparked interest, radio interference is a likely explanation, the senior astronomer said.
Efforts to corroborate the finding of the signal using other instruments did not yield any results.
The Russian Academy of Sciences too has said the signal is likely of terrestrial origin.
"There have been no scientific results within the framework of this research so far. Some time ago, in the spring of this year, an unusual signal was received but its analysis showed that it was most likely a terrestrial disturbance," RAS's Yulia Sotnikova reportedly said. According to the academy, this isn't the first time such a mystery signal was found. During the soviet era, a military satellite had caused similar disturbances.