The scientific search for extraterrestrial intelligence went global this weekend as observatories in 13 nations on five continents trained their telescopes on several promising star systems.

While they don’t expect their one-day joint effort will find the kind of intentionally produced signal from afar that enthusiasts have been seeking for decades, participants say the undertaking illustrates just how far the search for extraterrestrial intelligence — or SETI — has come.

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Dave Runkle is one of more than 1 million volunteers in a worldwide project in the search for extraterrestrial intelligence. Volunteers analyze radio wave data seeking an indication of intelligent life elsewhere. 1999 St. Paul Pioneer Press file

Frank Drake made the world’s first such observations at the Green Bank radio telescope in West Virginia 50 years ago, listening on a single-channel receiver that took in radio waves one frequency at a time. Today’s technology allows scientists to receive radio signals at millions of different frequencies per minute, in addition to searching for laser-like bursts of light communication using optical telescopes.

The international star-viewing extravaganza, the first of its kind, comes at a time of fast-paced discovery in the science of exoplanets, bodies that orbit stars beyond our solar system.

Last month alone brought the announcement of the first Earth-sized planet found that appeared to be potentially habitable, as well as a study from top scientists in the field which concluded that the number of Earth-sized planets in the Milky Way alone could be counted in the tens of billions.

“This is a real coming of age for exoplanets and for SETI,” said Drake, who remains active in the field and whose founding of the science of SETI five decades ago was being commemorated as well over the weekend.

“It shows SETI has gone truly international, and it’s happening when our knowledge about planets beyond Earth is just exploding,” he said. “We made predictions based on weak evidence 50 years ago and now a lot of that is, very satisfyingly, getting hard scientific support.”

Doug Vakoch, a SETI Institute scientist who helped organize the effort, said the coordinated observing is probably most important for its practical side.

“What this weekend really does is begin the process of making it possible to track a possible SETI signal around the globe,” he said. “If a signal is detected, it has to be confirmed and followed, and now we’re setting up a network to do that.”

The participating observatories are in Italy, India, Argentina, Australia, France, Germany, the United Kingdom, South Korea, Sweden, the Netherlands, and several in the United States and Japan.

The idea for the unprecedented global observation was initiated by Shin-ya Narusawa, director of Nishi-Harima Astronomical Observatory in western Japan.

The telescopes will be trained in a coordinated way on a number of star systems, including Tau Ceti and Epsilon Eridani — the nearest systems in the Northern Hemisphere and the two that Drake observed 50 years ago in what he called Project Ozma, a reference to the princess in “The Wizard of Oz.” (Keeping with the theme, the weekend’s effort is called “Project Dorothy” for the heroine of the book.)

“These two stars were the best SETI targets a half-century ago,” Narusawa said. “They remain the symbol of the project Ozma and so are two of the target stars for Project Dorothy.”

But with more than 500 exoplanets identified in the past 15 years and 700 more awaiting confirmation, he said, the observation can be far more directed and ambitious. Some will include stellar systems that have planets which appear to be located the right distance from their suns to support life, he said.

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