The Topaz Solar Farm in California, which covers 9.5 square miles (25.6 square kilometers), as seen from space. (Image credit: NASA Earth Observatory image by Jesse Allen, using Landsat data from the U.S. Geological Survey) Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Get the Space.com Newsletter Breaking space news, the latest updates on rocket launches, skywatching events and more!
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An account already exists for this email address, please log in. Subscribe to our newsletterWe may already be signaling other intelligences beyond our solar system, without even trying.
Kunyu City, in the Xinjiang Uygur Autonomous Region of northwest China, hosts huge sprinklers that are irrigating over 1,317 acres (533 hectares) of winter wheat fields on the southern edge of the Taklamakan Desert. Then there's the world's largest cluster of solar farms, a megaproject that covers 235 square miles (639 square kilometers) in Qinghai, China, high on the isolated Tibetan Plateau.
Visible signaling
People who want to reach out to E.T. have long recognized the communication potential of such "megastructures." In the nineteenth-century, for example, multiple folks advanced proposals for broadcasting "we're here" messages via visible signaling.
One popular type of proposal involved displaying supposedly meaningful figures on parts of our planet that would be visible from the extraterrestrial target of choice.
In these plans, recalled Douglas Vakoch, president of Messaging Extraterrestrial Intelligence (METI) International in San Francisco, huge diagrams would be etched on large expanses of land here on Earth. For example, a visual representation of a right triangle could be shown, he said, with a square attached to each side of the triangle to illustrate diagrammatically the Pythagorean theorem.
By clearing gargantuan stretches of forest, Vakoch said, such geometrical concepts could be seen by intelligent aliens scanning the sunlit side of the Earth. This intended, symbolic representation of the Pythagorean theorem would be huge enough to be seen from the moon — even by inhabitants of Mars.
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Hello, lunarians!
Vakoch said that among the early proponents of displaying pictures to communicate with extraterrestrials was the illustrious mathematician Karl Friedrich Gauss. In 1826, he was credited with suggesting such an approach for communicating with potential lunarians, inhabitants of Earth's moon.
"It was Gauss whose idea of inscribing the Pythagorean theorem in Siberian forests has often been touted as an early proposal for communicating with lunarians, although it's unclear whether Gauss actually said this, or whether it's only attributed to him," Vakoch told Space.com.
Similarly, there were thoughts of perhaps creating large canals in the Sahara Desert filled with kerosene, then torched to flash a similar transmission from the dark side of Earth, the METI expert explained.
Strip malls and data centers
Vakoch's favorite early proponent of interstellar communication is Francis Galton, an English polymath (and, less admirably, the originator of eugenics during the Victorian era). In 1896, Galton published an article in the "Fortnightly Review" called "Intelligible Signals Between Neighbouring Stars."
"Signals have to be devised that are intrinsically intelligible, so that the messages may be deciphered by any intelligent man, or other creature, who has made nearly as much advance in pure and applied science as ourselves," Galton emphasized.
So a bottom line: Are we viewed by other starfolk as a bunch of busy beavers terraforming our own planet while inadvertently waving to other worlds? If we build a big enough strip mall or AI data center, maybe we'll find out.
Leonard DavidSpace Insider ColumnistLeonard David is an award-winning space journalist who has been reporting on space activities for more than 50 years. Currently writing as Space.com's Space Insider Columnist among his other projects, Leonard has authored numerous books on space exploration, Mars missions and more, with his latest being "Moon Rush: The New Space Race" published in 2019 by National Geographic. He also wrote "Mars: Our Future on the Red Planet" released in 2016 by National Geographic. Leonard has served as a correspondent for SpaceNews, Scientific American and Aerospace America for the AIAA. He has received many awards, including the first Ordway Award for Sustained Excellence in Spaceflight History in 2015 at the AAS Wernher von Braun Memorial Symposium. You can find out Leonard's latest project at his website and on Twitter.
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