The ‘SETI’ Signal Likely Didn’t Come From Aliens

The last few days have been exciting for those looking for the signs of extraterrestrial life. In May 2015, a Search for Extraterrestrial Intelligence (SETI) team using the Russian RATAN-600 radio telescope detected an unusually strong radio signal coming from a star located about 94 light years away in the Hercules constellation. It was made public only a few days ago by Paul Gilster of Centauri Dreams.

SETI Signal RATAN-600
Image Credit: Wikimedia Commons

The SETI signal was detected just once in 39 scans

The radio waves were 4.5 times stronger than the background static. Astronomers are investigating whether the so-called ‘SETI signal” came from an alien civilization. The star HD 164595 is roughly the same age, mass, and metal composition as our own Sun. Astronomers already know that the star has a Neptune-size planet that orbits so close to its host star that it is just too hot to host life as we know it.

Of course, there could be other, undiscovered planets as well orbiting the star. However, there are many reasons to believe that the SETI signal might not have come from an alien civilization. First, astronomers at the Russian Academy of Sciences’ Special Astrophysical Observatory scanned the star HD 164595a total of 39 times and detected the radio signal only once.

RATAN-600’s north-south view ‘highly elongated’

By comparison, the Allen Telescope Array doesn’t even ask scientists to look at a potential candidate until it has detected a particular signal 12 times. Seth Shostak of SETI said we might never know the true origins of the signal without a follow-up detection. Every telescope has a “field of view”. The Russian RATAN-600 telescope covers a narrow east-west section that was centered on HD 164595.

But the telescope’s north-south view is “highly elongated,” according to Shostak. It means the real source of the radio waves could be anywhere in that elongated view. A “pixel” in the “field of view” lumps together all the signals from a specific area. So, the radio signals detected by RATAN-600 could be coming from north or south of the star HD 164595’s actual position.

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