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Aliens may be waiting for a cosmic version of “strong noon” to send us their signals, scientists have suggested.
In a new study, researchers looked for technological signs of ET during times when exoplanets pass directly in front of their suns, from Earth’s perspective. These exact times could be the perfect opportunity for an alien world to send a signal to Earthlings in an attempt to make contact.
“Exoplanetary transits are special because they can be calculated both by us on Earth, as observers, and also by any potential technological species in the exoplanetary system itself, as transmitters,” said the responsible for the study. Sofia Sheikh (opens in a new tab), postdoctoral researcher in radio astronomy at the Search for Extraterrestrial Intelligence Institute (SETI). These transits are therefore a predictable and repetitive period during which the extraterrestrials could think of sending messages and the Earthlings could seek to receive them.
Related: 12 Possible Reasons Why We Haven’t Found Aliens
“This strategy helps us reduce the huge question of where and when to search for a message in the vast expanses of space,” Sheikh told Live Science in an email.
The new study, published on December 9 on the prepublication site arXiv (opens in a new tab) and slated for peer-reviewed publication in The Astronomical Journal, found no evidence of talkative extraterrestrials. But the study only searched a dozen distant planets. In the future, they plan to look further with a variety of telescopes.
Related: Is it time to send another message to intelligent aliens? Some scientists think so. (opens in a new tab)
Since radio technology was invented at the end of the 19th century, Earth leaked transmissions into space – and sometimes, as with the famous Message from Arecibo from 1974 (opens in a new tab), deliberately sent them in hopes of contacting any intelligent extraterrestrials who might be listening. Hoping that intelligent alien civilizations might also be leaking technological signals, or technosignals, researchers are also scanning the galaxy for radio waves (opens in a new tab) which could be from extraterrestrial technology.
But the galaxy is a big place, so a key question is where to look. Sheikh and his team decided to listen to distant exoplanets as they pass in front of their suns, in what’s called a “Schelling point” – a solution to a problem that two individuals tend to solve by default if they do not communicate with another. In other words, the timing of the planetary transit seems like the logical time to connect from both the sender’s and the receiver’s perspective.
Sheikh and his colleagues used the Robert C. Byrd Green Bank Telescope in West Virginia to search for radio signals from 12 exoplanets whose transits were observable during a brief window in March 2018. They detected numerous radio signals – nearly 34 000, in fact – but 99.6% of that could be dismissed out of hand as interference from terrestrial communications. A group of trained citizen scientists carried out the work of examining the signals.
Ultimately, all but two of the signals were determined to be due to interference. The other two, short bursts of Kepler-1332b and Kepler-842b – two potentially rocky planets larger than Earth – were deemed worthy of further tracking. However, said Sheikh, these two are also almost certainly due to interference and are not real messages.
Still, she says, the study is proof that the research method can work. The researchers plan to tackle more observations in the future at the SETI Institute’s Allen Telescope Array in California.
Originally published on LiveScience.com (opens in a new tab).
