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SYFY WIRE Bad Astronomy

No, We Almost Certainly Did Not Detect an Alien Signal

By Phil Plait

The internets are buzzing with news that a Russian radio telescope detected a signal from a nearby Sun-like star and that it may be from an alien civilization.

I’ll ask you to read the title of this post again before I continue.

OK, got it? Here’s the thing: If we did detect a strong signal that had all the earmarks of an alien civilization, you’d be hearing SETI astronomers (and people like me) singing it from the rooftops. This ain’t that.

Here’s another thing: The signal is real, and may very well be from an intelligent civilization. That civilization, however, is us.

The signal appears to come from a part of the sky containing the star HD 164595, a star very much like the Sun, but located about 95 light-years away. It’s older than the Sun, likely a bit more than 6 billion years in age (the Sun is about 4.5 billion years old). It’s known to have at least one planet, what’s likely to be a gas giant with about Neptune’s mass, orbiting the star every 40 days. It may have other planets, but if so we haven’t detected them yet.

The signal was detected in May of 2015 and was a relatively weak but well-detected blip of energy at a wavelength of 2.7 cm (or a frequency of about 11 GHz if you prefer). The problem is knowing what it came from. The radio telescope, called RATAN-600 and located in Russia, has a relatively large beam pattern (you can think of it as the telescope’s ability to resolve objects that are close together). A lot of stars are in the area of the sky from which the signal originated, so it may not have come from HD 164595 at all. That’s just a guess on the part of the astronomers.

If it did come from that star, it was a powerful burst! My friend and SETI astronomer Seth Shostak calculates that at best it would take the entire human energy consumption rate to replicate it.

But the signal detected was the only signal detected. Only the one beep was seen, and despite SETI telescopes looking again and more carefully at the star, no other signal has been found. That seems like an odd course of action for aliens.

So what was it? It may have been natural in origin, a weird radio burst from a star or galaxy in the telescope’s field of view at the time. But it may have been unnatural: Astronomer Yu V. Sotnikova of the Special Astrophysical Observatory in Russia issued a statement saying the signal is likely “of terrestrial origin.” However, no other evidence for this was given. The frequency of the signal is near those used by the military and other human endeavors, so perhaps that’s what was meant by the statement.

Given all this, that seems the most likely scenario. I can’t say much about this for sure: It may or may not have come from that star, it may or may not have been natural, and it may or may not be from a military satellite or radar. But if I were a betting man—and I am— I’d wager heavily this was not from aliens.

I know, I’ve had to say something like this many times in the past few months, but that doesn’t make it any less true. If and when we ever do detect an alien signal, I trust my friends and colleagues at SETI will let us all know what they know as soon as they know. Until then, well, we’ll just have to keep looking. We’ll never find anything if we don’t look.

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