Milky Way has 4 'malicious' alien civilisations that could invade Earth, says Astronomer

The Milky Way most likely has four alien civilisations which might be malicious and can end up invading the Earth owing to the practice of METI. This statement is not ours but of Alberto Caballero, a Ph.D. student in conflict resolution at the University of Vigo in Spain who claims to have pinpointed the source of the WOW! signal. But before we understand what that signal is, it is important to know what is METI. Short for Messaging Extra-terrestrial Intelligence, METI is the practice wherein astronomers send encoded messages into outer space for aliens to find them and respond. 

What was the WOW! signal?

A few decades ago, the Ohio State University-based Big Ear telescope received a powerful burst of radio waves that turned out to contain an alphanumeric code. Having emerged in 1977, the signal lasted 72 seconds and was a big surprise for astronomers. The signal soon became of great interest of research and is considered the best candidate signal under the six-decades-old Search for Extra-Terrestrial Intelligence (SETI) program. 

Interestingly, Caballero claimed to have located the exact source of the signal, which is from a Sun-like star lying about 1,800 light-years away from Earth in the Sagittarius constellation.

There are four destructive civilisations out there: Caballero

The conflict resolution student estimates that there are four major "malicious extraterrestrial civilizations" hidden somewhere in the Milky Way galaxy. According to a report by Vice, Caballero revealed that he made these assumptions based on the calculations done on the number of external “invasions" that occurred on Earth in the last 50 years. He then applied the data to the number of known and potentially habitable exoplanets with Italian SETI scientist Claudio Maccone's estimate of the number of possible civilisations as a reference point. Maccone had made a wild claim that there are as many as 15,785 civilizations in our galaxy. 

It is worth noting, however, that Caballero's study is not peer-reviewed and it also admits that the probability of Earth being invaded by aliens is very, very low. For scale, it is two orders of magnitude lower than a planet-killing asteroid colliding with Earth. Besides, He himself admitted that his study has limitations but added that his work would open doors for conditions to send a radio message to the next habitable exoplanet.