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| All you have to do is call. |
Ever wish E.T. would phone your home? The scientists at the SETI (Search for Extraterrestrial Intelligence) Institute do. They seek unnatural variations in light and radio waves that may indicate alien civilizations. Some scientists even hope to send signals of our own out to the black, but it’s not easy to be seen and heard over all the stars, asteroids, and interstellar dust. We don’t have beacons powerful enough to reach the whole universe, nor receivers capable of monitoring the entire expanse. Other civilizations might, but there’s no way to tell until they finally hail us. All we know is how far our strongest signals could travel. Here’s where we’re searching—and where we fall short.
Don't blink
To keep an eye out for distant lasers that could head toward our neighborhood, we have to watch the entire sky. SETI plans to put 96 cameras at 12 sites across the world to monitor for flashes as brief as a millisecond or less. Shine on, aliens.
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| Atmosphere is key. |
Start simple
Life doesn’t have to be intelligent. By looking for planets with out-of-whack atmospheres (like ours, with its imbalance of oxygen and methane), we could figure out what worlds may have developed life. That narrows the search for interstellar smarties.
Laser
If aliens use light-propelled spacecraft—like those proposed by the Breakthrough Starshot program—we might spot flashes from across the galaxy. We could also shine a laser of our own, hoping to strike where an alien is paying attention.
We are here
“We joke that the first message extraterrestrials will pick up is I Love Lucy,” says SETI’s Jill Tarter—it was among the first big broadcasts. But Lucy’s light-speed antics are pretty garbled by now. If whatever signal remains has reached anyone, it clearly hasn’t inspired a reply.
Radio nowhere
You can make a radio outburst travel farther by narrowing its beam. Radio telescopes send out pointed broadcasts that should persist halfway to the center of the galaxy (we’re near the edge) before blending into the noise of cosmic radiation.
