The pattern showed up in old telescope data: Weird variations in the light patterns of about 230 stars. The astronomers—a pair of Canadians—published their analysis, along with what they believed was the culprit: Aliens.
SETI researchers quickly countered that the patterns were probably just artifacts from analyzing the data, and the Breakthrough Listen project published a response pointing out several flaws.
Caveats aside, the Breakthrough Listen rebuke also assigned the finding a number: 1. According to the Rio scale—used by SETI researchers to assess the likelihood that a suspected alien signal actually came from ETs—that means the finding is "insignificant." That's one above 0 (“no importance"), and nine below a perfect 10 (“extraordinary”). Not quite a scientific tool, the scale's main purpose is to inform the public. Which is important for SETI, a field constantly guarding its scientific cred—while talking about aliens. And the scale isn't perfect, but SETI scientists are now working on revamping it and using it in earnest.
The scale originated (naturally) with an internet hoax. In 1998, a British man claimed he had detected a signal emanating from the star system EQ Pegasi and sent a tip to the BBC, who broke the story. “The media jumped on it right away,” says Seth Shostak, a senior astronomer at the SETI Institute. The SETI community tried to quash the story, and it was eventually debunked, but scientists wanted to head off future hoaxes. So, at a 2000 conference in Rio de Janeiro, astronomers Jill Tarter and Ivan Almar presented a paper laying out their scheme for the scale.
Essentially, the (so named) Rio scale takes into account the following: What was the observation? (An intriguing radio signal? Flashing laser beams? An actual, physical encounter?); How far away did it originate?; How often did it occur? Those factors, lumped together, are multiplied by the report's credibility—did it come from a credentialed university group, or some internet rando?
Ready to calculate? The International Academy of Astronautics has a handy online calculator!
Scientists can go back and grade past signals on the scale, like the famed 1977 Wow! signal, which gets anywhere from a 1 to a 3. But that variable range exposes a problem with the Rio scale. Astronomers complain that there’s no standardization to using the scale, no repository where the ratings of past signals are kept, and no standard announcement process (that people follow). It’s mostly used on an ad hoc basis, and some astronomers don’t even know it exists.
And that's all in addition to a few major flaws. First, the Rio scale is hard to use on the fly. It asks for a lot more information than is typically available in a lot of cases. “By the time you have all the information, the story’s already gone,” Shostak says. There goes the usefulness to the public. Plus, it assumes that you’re dealing with aliens in the first place, which just isn’t true most of the time. And deciding what sources are credible can get subjective.
But scientists still use the scale. During an advisory board meeting for the Breakthrough Listen project this year, the board recommended that astronomers make a concerted effort to use the scale and standardize their responses to it. “It’s even more pertinent in 2016 given the way news is reported now, with social media and shorter news cycles online,” says Steve Croft, a radio astronomer at the project.
Plus, it’s good for controlling expectations, says Eric Korpela, the head of the SETI@home project at UC Berkeley—it’s hard for a possible signal to even get a 2. “People tend to be disappointed when we don’t find anything,” he says. “The scale gives them some realism.”
But the Rio scale is just one answer to a bigger problem of SETI stories getting away from scientists in the news. Bad press has shaped the science of looking for extraterrestrial life—in one memorable instance, by Congress pulling the plug on a NASA project in 1993 after a Congressman accused it of wasting taxpayer money and called it a "great Martian chase." (The field has largely been funded by private donors ever since.)
So when reports of alien signals pop up in the news, SETI scientists tread a delicate line: they have to respond with extreme skepticism because once things get overblown, it makes the work of everyone else in the field look a little less legit. No matter how much they believe the truth is out there.
