The hunt for aliens isn’t as sensational or speculative as you might think. In fact, astronomers are constantly inventing practical ways to search for intelligent life in our universe. Research recently published in the Astronomical Journal describes a pioneering method to look for radio beacons at the center of the Milky Way—a new idea for how extraterrestrials might send us signals. (Spoiler: the study authors didn’t find any beacons…yet!)
Astronomers have been scanning the sky with radio telescopes since the dawn of the Search for Extraterrestrial Intelligence, or SETI, in the 1960s, when they began listening for technological messages from the stars. In particular, they’ve been looking for so-called narrowband signals—blips of radio waves that occur over a very small range of frequencies, which couldn’t be produced by nature. Narrowband messages generally have to target a specific star, whereas a centralized radio beacon could cast a wide net, sweeping across the galaxy.
“This paper is hugely important for the Search for Extraterrestrial Intelligence because it contains the first large survey for radio technosignatures that are periodic,” says SETI Institute astronomer Sofia Sheikh, a co-author on the new work. Periodic means these signals would be “flashing over time like a lighthouse,” she says, “instead of assuming that the signal has to be on continuously like a streetlight.”
Sheikh and other collaborators, including Cornell University astronomer Akshay Suresh, propose these repeating pulses of radio emission could originate from some sort of rotating beacon. If situated at the center of the galaxy, such a beacon could be a particularly efficient way of communicating across vast distances. The signals from this kind of beacon may also be easier to find while sifting through radio data, which is often contaminated with the omnipresent buzzing of Earth’s technology.
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