Social media and news outlets the past few days have been abuzz with the prospects of a strong signal apparently coming from the star unromantically known at HD 164595, which is about 94 light years from Earth. Reading news reports, one would think that the signal was intercepted last week, but actually it was picked up over a year ago in May of 2015.
Indeed, the buzz is reminiscent of extensive news coverage that surrounded KIC 8462852, now known as Tabby's Star, last year when it was suggested by Penn State astronomer Jason Wright that the star's odd dimming behavior might be the result of an alien civilization building a mega-structure blocking the star's light. We've also seen recent fascination with the discovery of a rocky planet orbiting inside the habitable zone around Proxima Centauri, which is quite near (by galactic standards) Earth at a little over 4 light years distant. It's our next-door neighbor.
Scientists have been careful in expressing optimism over these unusual discoveries, noting that neither of the candidates for extraterrestrial civilizations are anything more than interesting at this point. There is no evidence right now that something artificial is going on either around KIC 8462852 or HD 164595 and it's not even certain that the signal under discussion now came from HD 164595.
Both METI International, using the Boquete Optical SETI Observatory in Panama, and the SETI Institute, using the Allen Telescope Array in California, have plans to train their observational equipment on HD 164595 to see if anything interesting might emerge that supports, or discounts, the idea that the signal was artificial. Perhaps something intriguing will show up.
However, SETI astronomer Seth Shostak makes several good points about the problems with HD 164595 being a signal from a civilization. For example, it would have required a great deal of power to generate the signal we received -- either the equivalent of all of humanity's power usage on Earth if it were aimed directly at us or the equivalent of the entire power output of the Sun if the broadcast was omnidirectional.
Neither of these conditions are impossible, but they should raise eyebrows. Oddly enough, it's the argument for the lower level of power usage that should raise significant questions. If the signal were a beacon aimed at Earth, we are forced to ask, why? At 94 light years away, as Shostak notes, our television and other signals have not yet had time to reach HD 164595. How would they know we are here? Of course, 94 years ago they may have had technology that would allow them to detect our presence, even if we were not sending out much in the way of signals at that time. But it's difficult to imagine how they would pick up the presence of Earth civilization as it existed in 1920. And if they were somehow able to do this, why would they send a message to a civilization that didn't look as though it could respond?
Perhaps they are both prescient and very patient. They knew that a century later, humans would have the capacity to send out signals at the speed of light, so they anticipated that. And they are patient enough to wait two centuries for an answer.
This explanation is possible, but if that alien civilization were anything like us, it would seem pretty unlikely. It's best to expect other explanations will work better for this signal until we have more evidence. Of course, if the signal doesn't appear again, it may be little more than another fascinating data point like the WOW! Signal, that showed up once leaving little more than a tantalizing mystery.
The public and news media should keep in mind that science is a system of organized skepticism. And it's that way for a good reason; skepticism keeps us from drawing unwarranted conclusions from what we observe. When it comes to SETI, we should avoid getting too excited about possible signals of artificial and extraterrestrial origin, because usually there is a better explanation than little green men from Alpha Centauri, whether or not it's a beautiful place that we ought to see.