Let’s be careful about this “SETI” signal

[ 3 ] Comments

August 31: See update at the end of this post

Several readers have contacted me recently about reports that a group of international astronomers have detected a strong signal coming from a distant star that could be a sign of a high-technology civilization. Here’s my reaction: it’s interesting, but it’s definitely not the sign of an alien civilization—at least not yet.

Jodie Foster in the movie "Contact"

Jodie Foster in the movie “Contact”

Here’s why:

  1. The signal was first detected in May 2015 and has not repeated since. Unfortunately, although international protocols call for alerting the astronomical community to the detection of a mysterious signal, the observers chose not to do so. Sadly, their failure to observe this simple protocol likely hindered our ability to clarify exactly what caused the signal.
  2. The signal was detected by an antenna that is very complex—and one that a colleague of mine who is a radio astronomer said could have mislabeled a terrestrial signal (i.e, one from a satellite or airplane) crossing the side lobes of the beam when the observation was made. In other words, the pointing quality of this antenna is so uncertain that it may have captured what we call a false or “parasite” signal.
  3. HD 164595, the host star, is very similar to the sun (same color, size, and age). It’s ninety-one light years from Earth and has a known planet, HD164595 b, which is probably Neptune-like and orbits very close to its star every forty days. We have not yet detected an Earth-like or super-Earth-like planet around this star, and do not believe there is one. This is the case because this is what current theories on the formation of planetary systems tell us. But there is no reason why life could not exist on satellites of as-yet undetected icy giants in this system—but this moves us from fact to the realm of pure speculation.
  4. Finally, before getting too excited about a speculative and relatively old signal, we should recall the puzzle of the perytons. Astronomers detected them at the Parkes Observatory in Australia in 2015, only to later conclude that they were nothing more than the signal from a nearby microwave oven whose door was opened by impatient astronomers.

But—and it’s a big but—I began this post by saying “at least not yet.” So what might cause me to change my mind? How might we prove the extraordinary claim that this signal is, in fact, a civilization trying to communicate with us?

We turn to this mantra from Carl Sagan: “Extraordinary claims require extraordinary evidence.” That means three things:

First, this signal must be detected by at least one other antenna located somewhere else in the world. My colleagues at the SETI Institute are already working on it, and have observed the star for several hours.  So far they have nothing to report.


Second, we must analyze the signal to be certain that it is not coming from a human source.

Third, if the signal is detected repetitively, we can analyze it under the assumption that it might have content E.T. wants to share with us. Whatever that message might be—the digits of Pi, the first prime number, their encyclopedia, or some images of themselves—we can quickly find out if ET is trying to tell us something, and what that something is.

We are not there yet. In the past, especially during the tumultuous history of SETI, astronomers briefly thought that they had discovered a signal (see “Aliens on Line 1”). As technology evolves, and more searches occur, we may discover more signals that look promising at first but don’t pan out. But the search continues… in fact, in the scale of the age of our solar system, it has just begun.
Clear Skies,

Franck Marchis

August 31 2016  Update:

In contrast with all the hypes about this hypothetical signal, I must admit that I love the dry, not marketing-oriented, note from SAO RAS, the team that managed the Russian RATAN-600 antenna. https://www.sao.ru/Doc-en/SciNews/2016/Sotnikova/

“Subsequent processing & analysis of the signal revealed its most probable terrestrial origin”

Apparently, there has never been a SETI signal, not even a candidate one.


About Franck Marchis

Dr. Franck Marchis is a Senior Researcher and Chair of the Exoplanet Group at the Carl Sagan Center of the SETI Institute since July 2007. Over the past 19 years, he has dedicated his research to the study of our solar system, specifically the search for asteroids with moons, using mainly ground-based telescopes equipped with adaptive optics. More recently he has been also involved in the definition of new generation of AOs for 8 -10 m class telescopes and future Extremely Large Telescopes. He has developed algorithms to process and enhance the quality of images, both astronomical and biological. His currently involved in the Gemini Planet Imager Exoplanet Survey, which consists in imaging exoplanets using an extreme AO system for the Gemini South telescope. This new instrument is be capable of imaging and recording spectra of young Jupiter-like exoplanets orbiting around nearby stars.

3 Responses to Let’s be careful about this “SETI” signal

  1. Skyler says:

    Exciting nonetheless! We need more stories like these to keep up the hype and get more involved and informed in this kind of work. I agree, certainty is absolutely needed, but just the fact there’s a chance is enough to stir a furious curiosity. I’ll be keeping an eye out for updates. One day, I believe we’ll find something. Thank you for your important work.

  2. Greg Peschin says:

    Why is Jodie Foster listening to Procol Harum in the middle of a Radio Telescope Array?

  3. Edgar says:

    It’s absurd to even believe humans are alone in this universe. But evidence shows a different story according to our present technology and knowledge. Maybe one day we’ll be able to reach the stars ourselves and know the truth, but we’ve a long way to go, if we make it in our current war-like state of mind.

    If there are beings more advanced than us out there, our war-like state might be the reason they would prefer to stay hidden from us. They’ve done a good job so far at baffling the human mind.

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