Category: Astronomy

A new analysis from astronomer Michael Garrett at the University of Manchester suggests intelligent civilizations across the galaxy may only emit detectable signals for a short period between 100 and 1,000 years before becoming effectively invisible.

The finding could help explain why decades of SETI (Search for Extraterrestrial Intelligence) surveys have yet to detect alien broadcasts, despite the vast number of potentially habitable planets in the Milky Way.

Garrett’s research focuses on how fast technology evolves once a species gains the ability to communicate wirelessly. His models show that once a civilization masters radio or laser communication, it quickly moves toward more efficient, secure, and low-energy systems. That means their detectable “loud” phase when they leak or beam out radio signals may be brief compared to the billions of years that stars and planets exist.

“We may be missing them by timing alone,” Garrett said in a University of Manchester release. “Civilizations likely go silent quickly, not because they vanish, but because they stop using technologies we can detect.”

The idea offers a fresh take on the Fermi Paradox, the question first posed by physicist Enrico Fermi in 1950: if life is common, why haven’t we found it? Garrett’s calculations imply that many civilizations could exist, but only a tiny fraction would overlap with our brief listening window.

On Earth, radio broadcasts began just over a century ago, with satellite and digital networks reducing our own signal leakage since the 1990s. In another few centuries, Garrett predicts, our outward radio footprint could disappear completely as fiber optics and quantum networks replace open transmissions. From another planet’s point of view, humanity might already be fading from the galactic map.

The study also considers the problem of energy growth. Rapid advances in computing and communication efficiency mirror trends similar to Moore’s Law. As societies expand technologically, they risk overheating their worlds if energy use grows unchecked.

A 2024 paper from the University of Rochester estimated that continued exponential energy use could raise planetary temperatures to uninhabitable levels within a thousand years. To survive, civilizations must shift toward compact, low-emission technologies, which would also make them harder to detect.

Garrett argues that SETI strategies should adapt to this reality. Instead of focusing mainly on radio signals, he suggests searching for indirect evidence: infrared emissions from large-scale solar collectors, starlight dimming from partial Dyson spheres, or even unusual neutrino bursts from advanced communications. Such signs would point to mature societies that still exist but no longer radiate traditional signals.

Astronomers are already expanding the search in this direction. NASA’s Technosignature Program and projects like Breakthrough Listen are using machine learning to scan vast datasets for subtle anomalies. Instruments such as the Australian Square Kilometre Array Pathfinder (ASKAP) in Western Australia and the upcoming SKA Observatory are expected to play key roles in identifying potential technosignatures that might otherwise go unnoticed.

Garrett’s model also encourages researchers to examine Earth’s own future as a guide. Studies at NASA’s Goddard Space Flight Center simulate how our planet might appear to distant observers 1,000 years from now, showing declining radio output but a growing technosphere of satellites, solar arrays, and artificial light. Understanding how our signal fades could help scientists recognize similar transitions elsewhere.

While the findings narrow the odds of intercepting a message, they also reshape expectations. The universe may not be silent; it could be full of civilizations operating in communication modes we have yet to understand. For scientists, the next step is widening the search beyond traditional radio frequencies to the full spectrum of possible technologies.

“If intelligence survives long enough, it becomes quieter,” Garrett said. “The challenge for us is to learn how to listen differently.”

Source: Projecting what Earth will Look Like 1000 years from now Could Assist in the Search for Advanced Civilizations

The Sunset Bay Astronomy Festival will return to Oregon’s coast from September 25 to 27, offering three nights of star parties, hikes, and family-friendly activities at Sunset Bay and Shore Acres state parks near Coos Bay. Organizers say the annual event gives visitors a rare chance to see the night sky free from city light pollution while learning more about the universe.

The festival opens Thursday evening with a photography workshop led by park staff, where participants can learn how to capture the Milky Way and other celestial scenes using long-exposure techniques.

Throughout the weekend, guided hikes and interpretive talks will introduce visitors to natural features and constellations visible in the September sky. Children can take part in junior ranger programs designed to explain basic astronomy in simple terms.

Each night at 8 p.m., Shore Acres will host a star party with telescopes set up by operators who guide the public through views of Saturn, star clusters, galaxies, and the arc of the Milky Way. Park manager Lee Ricci says the setting allows people to see up to 2,500 stars on a clear night, compared to a few hundred in most cities.

Astronomers point out that the timing offers good viewing conditions. Late September skies feature the autumn constellations, including Pegasus rising in the east. Saturn may still be visible low in the west, while the Andromeda Galaxy can sometimes be spotted with the naked eye. The moon will be in its crescent phase during the festival’s first nights, leaving skies darker for stargazing.

Visitors are advised to dress warmly, bring a red-filter flashlight to protect night vision, and download a stargazing app to help identify what they see. Parking at Shore Acres requires a $10 day-use permit. Because events depend on weather, attendees are encouraged to check forecasts before traveling.

To join the photography workshop, advance registration is required by emailing Kenneth.Page@oprd.oregon.gov.

For more information on schedules and activities, contact Rose Shimberg at rshimberg@salem.gannett.com, who is covering the event for local media.