The hardest part of listening for alien radio signals may not be where to point the telescope. It may be when. A civilisation with a powerful transmitter would have little reason to broadcast in every direction, all the time, at enormous energy cost. A focused beam sent at a well chosen moment is cheaper, but only if someone is listening at that moment. A new survey from the SETI Institute bets on one particular time and place, the anti-solar point, and has now published its first results.
Led by Sofia Sheikh and Eleanor Hort of the SETI Institute, the paper appeared in The Astronomical Journal on 3 November 2026. According to the institute’s announcement, it sets out the design of a multiyear radio campaign with the Allen Telescope Array at Hat Creek Radio Observatory in Northern California, and reports a pilot run from the summer of 2023. The pilot found nothing artificial from beyond Earth. That was expected, and it is not the interesting part.
What is interesting is the reasoning, which borrows from game theory, specifically the economist Thomas Schelling’s idea of a focal point: a choice two parties can each arrive at without ever talking to each other. The classic illustration asks two strangers to meet somewhere in New York with no time or place agreed. Many would settle on Grand Central Terminal at noon. Each guesses what the other will guess, and the obvious answer wins.
Now apply that to two civilisations. Astronomers on Earth find most exoplanets by the transit method, watching a star dim slightly as a planet crosses its face. Anyone using the same trick from a planet near the plane of our Solar System could watch Earth cross the Sun. At the midpoint of that transit, the distant observer, Earth and the Sun all sit in a line. Seen from Earth, the observer would then lie directly opposite the Sun in the sky. That spot is the anti-solar point, and it offers both sides a shared clock. As Sheikh puts it, the hard part is “figuring out where and when another civilization might choose to transmit.”
Because Earth moves around its orbit, the anti-solar point creeps along the ecliptic, the Sun’s yearly path across the sky. The survey therefore cannot stare at a fixed list of stars. It returns two to three nights a week, chasing the point around the whole ecliptic over roughly four years. The pilot used 20 of the array’s antennas for about 17 hours, collecting some 32 terabytes of data. Software called ATSAT then hunted for narrowband signals, the kind of sharp, single frequency tone that nature rarely makes but transmitters do.
It flagged about 1.9 million candidate “hits”. Every one could be traced to human sources: satellites, communication systems and the general radio clutter of a wired planet. To sort local noise from the sky, the team forms two beams at once, one on the anti-solar point and one on a nearby patch of sky. A real distant signal should appear in only one. Under the paper’s assumptions, the pilot could have caught a transmitter as powerful as the former Arecibo planetary radar out to about 124 light-years.
Since the pilot, the full campaign has grown far larger, with more than 121 nights logged. A companion preprint by the same group, posted to arXiv and not yet peer reviewed, describes 87,660 planned pointings across frequencies from 2,356 to 3,700 MHz. As of 12 September 2026, about 12 per cent were done. That preprint also lists 25 signals of interest that survived its filters and are scheduled for another look; it claims no detection.
The catch is the premise itself. The strategy works only if a hypothetical sender reasons exactly as we do: that it uses transits, that it cares about Earth, and that it corrects its timing for the years its signal will spend crossing space. The geometry also limits the search to stars lying close to the ecliptic, a thin slice of the sky. Satellites keep multiplying, and with them the interference the pipeline must reject. The authors are open that none of this assumes anyone is out there to send a signal at all.
Even so, the approach has a practical virtue. SETI has always struggled with a search space too large to cover, and a null result from an untargeted survey says little. A defined hypothesis turns silence into a measurement: if no one is transmitting at the anti-solar point above a given power, that box can be ticked.
The approach also turns the usual question around. Instead of asking where aliens might live, it asks what they might expect of us. The answer, at least for now, is a polite appointment with an empty chair.
