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Rio Scale

April 14, 2017

Weather forecasts tell us the odds that it’ll rain tomorrow. Betting lines tell us the odds that one team will beat another. And the Rio Scale tells us the odds that a possible signal from ET is either the real thing or just wishful thinking.

Scientists developed the Rio Scale almost two decades ago, after reports of the discovery of intelligent signals from another star turned out to be a hoax. The scientists wanted an easy way to rate the odds that a possible discovery was the real deal — not only for themselves, but for the media and public as well.

So during a conference in Rio de Janeiro, Jill Tarter and Ivan Almar devised a rating system. It evaluates two main factors. One is the importance of a possible discovery. A signal from a star a few light-years away — one we could communicate with over a human lifetime — rates higher than a signal from a star across the galaxy.

The other factor is the credibility of any reported discovery. A signal that’s been detected several times by reputable institutions would get a higher rating than a signal heard by a guy with a backyard radio dish.

When those two factors are combined, they produce a number from zero to 10. Right now, the only discovery that rates as high as a 3 or 4 is Tabby’s Star — an odd system in which many objects routinely pass in front of the star, blocking some of its light. That doesn’t mean ET is there, only that it’s worth doing some more looking — just in case.


Script by Damond Benningfield

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