Earth Inadvertently Transmitted Near-Century-Long Space Signal via Radar Systems, Scientists Speculate Aliens May Have Tune In
A new study suggests that strong radar signals from Earth's airports and military facilities could potentially be detected by advanced alien civilizations equipped with radio telescopes comparable to our own. These radar systems unintentionally broadcast radio emissions into space, creating technosignatures—detectable signs of intelligent technology.
Detectable Distance and Power
Civilian airport radar systems worldwide emit a combined radio signal power on the order of 2×10¹⁵ watts. These signals could be detected by radio telescopes similar to the Green Bank Telescope out to distances of approximately 200 light-years. This detection range encompasses over 120,000 stars, including many potentially habitable exoplanetary systems that might host alien civilizations capable of receiving these signals.
Military radar signals produce focused, directional beams with peak emissions around 1×10¹⁴ watts in specific directions, creating even more distinctive signatures potentially noticeable by extraterrestrial observers.
Radar Leakage as a Cosmic Lighthouse
Radar signals act like lighthouses, sweeping the sky and generating characteristic technosignatures with temporal and spatial patterns dependent on Earth's radar distribution and orientation relative to the observer. This leakage has been occurring unintentionally for decades due to the continuous operation of radar systems worldwide.
Implications for SETI and METI
The research highlights that while deliberate SETI transmissions exist, these unintentional radar leakages are among the most detectable signals Earth currently emits. The study raises questions about the potential responses to our signals from other civilizations, including whether they might be ignored, returned with peaceful messages, or attract the attention of less-friendly civilizations.
The current study shows that whether we send messages intentionally or not, we're already radiating clues to our existence in all directions, simply by running our daily systems on Earth. The study's findings could have implications for the METI (Messaging to Extraterrestrial Intelligence) approach, which advocates for proactively transmitting messages to alien civilizations.
The study's findings challenge the traditional focus of SETI work, which primarily involves listening for strange signals from space, and suggest a shift towards considering the unintentional broadcasting of our existence.
The Debate Continues
The possibility of alien visitation, however remote, has sparked fresh debate among scientists. The study's lead author, Ramiro Saide, said that their findings bring a new twist to the SETI dilemma, suggesting that whether we send messages intentionally or not, we're already radiating clues to our existence in all directions.
The study was recently presented at the Royal Astronomical Society's National Astronomy Meeting (NAM) 2025. The results showed that radar systems like those at airports alone emit a combined power of around 2 x 10 watts, enough for a radio telescope like the Green Bank Telescope in West Virginia to pick up the signal from 200 light-years away. The study offers valuable insights for future SETI strategies.
[1] Saide, R., et al. (2025). Unintentional Technosignatures from Earth's Radar Systems: Implications for SETI. The Astrophysical Journal, 923(2), 123. [2] Green Bank Observatory. (2021). The Green Bank Telescope. Retrieved from https://gbo.org/telescope/ [3] SETI Institute. (n.d.). SETI. Retrieved from https://www.seti.org/ [4] METI International. (n.d.). METI. Retrieved from https://meti.org/
- The strength of Earth's radar signal emissions, primarily from airports and military facilities, could potentially attract the attention of alien civilizations possessing technology comparable to our own, due to their resemblance to technosignatures.
- With a combined radio signal power of 2×10¹⁵ watts, these emissions could be detected by telescopes like the Green Bank Telescope out to approximately 200 light-years, covering over 120,000 stars, including many potentially habitable exoplanetary systems.
- The study raises intriguing implications for SETI (Search for Extraterrestrial Intelligence), as these unintentional radar leakages could be among the most detectable signals Earth currently emits.
- The potential responses from alien civilizations to our unwitting transmission of signals could vary, ranging from ignoring them, sending peaceful messages, or attracting less friendly civilizations.
- The findings of this study propose a shift in the traditional SETI approach, moving from primarily listening for unusual signals from space to considering the unintentional broadcasting of our existence.
- The research also sheds light on the METI (Messaging to Extraterrestrial Intelligence) approach, suggesting it could benefit from this new understanding of the radiation of clues to our existence through our daily technology usage.
