Part 3 of the TED Radio Hour episode Citizen Science.
About Tabetha Boyajian's TED Talk
In 2009, the Kepler telescope was sent out to search for other planets. But when astronomer Tabetha Boyajian asked thousands of amateurs to comb through Kepler's data, they found something entirely unexpected.
About Tabetha Boyajian
Planet hunter Tabetha Boyajian studies KIC 8462852 (dubbed "Tabby's star"): a star exhibiting bizarre variations in brightness. These fluctuations have led to a host of theories ranging from comet dust to alien megastructures.
Boyajian is a postdoc with the Yale Exoplanet group, whose research is assisted by the Planet Hunters — a citizen science group that combs data from the NASA Kepler Space Mission for evidence of exoplanets and other unusual interstellar activity.
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GUY RAZ, HOST:
On the show today, Citizen Science - ideas about human curiosity and the power of ordinary people to find answers from the bottom up. And this next discovery, it started back in 2009 when NASA launched the Kepler mission.
TABETHA BOYAJIAN: It was so simple. What it did is that, you know, it had, you know, this gigantic camera that was very, very precise. And it stared at a single patch of sky for four years straight taking very precise measurements of how bright the stars in that one patch of sky was.
RAZ: This is Tabetha Boyajian.
BOYAJIAN: I'm a professor at Louisiana - excuse me. I'm a (laughter) - say that over again (laughter).
RAZ: Yeah, please, sure. No problem.
BOYAJIAN: This is a really hard question (laughter). I am a professor of astronomy at Louisiana State University.
RAZ: So anyway, this Kepler mission.
BOYAJIAN: It was looking at over 150,000 stars in this one patch of sky.
RAZ: And the idea was - what? What was the ultimate idea to kind of find out?
BOYAJIAN: The ultimate goal was to determine the frequency of Earth-like planets around other stars. So how common is Earth out there?
RAZ: Yeah. It's hard to see - right? - because so many of these planets are dark, right? We may not see them because there's no light that shines on them, right?
BOYAJIAN: Right. Well, that's actually what we use. So we use a technique called the transit technique. And what this does is you monitor a star and you wait for the chance alignment of a planet that's orbiting the star to cross in front of it and block out some of the light. So we actually use the fact that the planet itself is very dark against the star. And we're looking for that little blip in the star light that's due to the planet crossing in front of it.
RAZ: Here's Tabetha Boyajian on the TED stage.
(SOUNDBITE OF TED TALK)
BOYAJIAN: And so the team at NASA had developed very sophisticated computers to search for transits in all the Kepler data. At the same time of the first data release, astronomers at Yale were wondering an interesting thing - what if computers missed something? And so we launched the citizen science project called Planet Hunters to have people look at the same data.
The human brain has an amazing ability for pattern recognition, sometimes even better than a computer. However, there was a lot of skepticism around this. My colleague, Debra Fischer, founder of the Planet Hunters project, said that people at the time were saying you're crazy. There's no way that a computer will miss a signal. And so it was on - the classic human versus machine gamble.
And if we found one planet, we would be thrilled. When I joined the team four years ago, we had already found a couple. And today, with the help of over 300,000 science enthusiasts, we have found dozens. And we've also found one of the most mysterious stars in our galaxy.
(SOUNDBITE OF MUSIC)
BOYAJIAN: The Planet Hunters came across this one light curve from a star that didn't really fit into a classification of any other star that we know of.
RAZ: What do you mean?
BOYAJIAN: It was a transit-like dip in the star's light, meaning that it kind of went down and back up again. But it was noted on the website that this was kind of giant, meaning that, you know, instead of a transit lasting for a couple of hours, this one lasted for over a week.
RAZ: A week - the star dimmed for a week?
BOYAJIAN: Yeah, that's right. And then in 2011, we see a single but very significant - this thing went over 15 percent drop in the star's light. But it was a single event. And then in 2013, almost two years later, that's when things start to get really crazy.
RAZ: Now, this light curve was a huge anomaly in the data because nothing else had looked like this ever before.
(SOUNDBITE OF TED TALK)
BOYAJIAN: There is a huge complex of dips in the light curve that appear. And they last for, like, 100 days all the way up until the Kepler Mission's end. These dips have variable shapes. Some are very sharp and some are broad. And they also have variable durations. Some last just for a day or two and some for more than a week. And there's also up and down trends within some of these dips, almost like several independent events were superimposed on top of each other.
And at this time, this star drops in its brightness over 20 percent. This means that whatever is blocking its light has an area of over a thousand times the area of our planet Earth. This is truly remarkable. And so the citizen scientists, when they saw this, they notified the science team that they found something weird enough that it might be worth following up. And so when the science team looked at it, we were like, yeah, there's probably just something wrong with the data.
But we looked really, really, really hard. And the data were good. And so what was happening had to be astrophysical, meaning that something in space was getting in the way and blocking starlight. And so at this point, we set out to learn everything we could about the star to see if we could find any clues to what was going on. And the citizen scientists who helped us in this discovery, they joined along for the ride, watching science in action firsthand.
RAZ: So eventually, people started coming up with their own theories about what was causing this mysterious dip in the light. And they started to share those theories with each other online. Now, some of them thought it could've been caused by comets.
BOYAJIAN: Several hundred, like, Halley-size comets. And that's really big. And that's a whole lot of them.
RAZ: And then others thought it might be caused by the star itself.
BOYAJIAN: You know, it gets bright and then it kind of, like, jiggles down a little bit.
RAZ: Or maybe even something around it.
BOYAJIAN: Something like a super-Saturn type object.
RAZ: And then one guy...
BOYAJIAN: This idea came from Dr. Jason Wright at Penn State University.
RAZ: ...He thought it could be caused by something else entirely.
BOYAJIAN: He was working on a paper that also used Kepler data. And what he was doing is he was testing the idea that Kepler could have detected alien megastructures.
RAZ: You mean like the Death Star?
BOYAJIAN: Well, believe it or not, the Death Star would be very easy to model because it is so round. So we're talking something that's really, really, really big, much, much bigger than a planet. And, you know, the whole idea here is...
RAZ: Like Jupiter-sized.
BOYAJIAN: Much bigger than Jupiter, too.
RAZ: Much bigger than Jupiter?
BOYAJIAN: Much bigger than Jupiter.
RAZ: How many aliens would it take to build that?
BOYAJIAN: (Laughter) It would be an enormous amount of material.
RAZ: I'm just thinking about the, like, the scaffolding of alien - like, you know, aliens on those scaffolds, like, trying to build that giant megastructure. That's going to take a long time.
BOYAJIAN: Right, right. Well, I mean, if you're talking - you see, the dip in the light at most is 22 percent. It would take over 50 Jupiter-sized objects to block out that amount of light.
BOYAJIAN: And that's just at that one period of time. And that's just the amount of whatever's blocking it that crosses in front of the star 'cause you could have, you know, part of it above the star or below the star. You're not getting that signal in the data.
(SOUNDBITE OF TED TALK)
BOYAJIAN: Well, there you have it. We're in a situation that could unfold to be a natural phenomenon we don't understand or an alien technology we don't understand. Personally, as a scientist, my money's on the natural explanation. But don't get me wrong, I do think it would be awesome to find aliens. So what happens next? We need to continue to observe this star to learn more what's happening.
But professional astronomers like me, we have limited resources for this kind of thing. And Kepler is on to a different mission. And I'm happy to say that once again, citizen scientists have come in and saved the day. You see, this time, amateur astronomers with their backyard telescopes stepped up immediately and started observing this star nightly at their own facilities.
And I am so excited to see what they'll find.
RAZ: Could this have been discovered and examined without the participation of thousands of citizen scientists?
BOYAJIAN: I really don't think so because before we knew about this star, we didn't really know what to look for. And all the searches before using this data had, you know, looked for something that was periodically appearing. So that's, you know, planets or some sort of variability, what have you. This signal was huge in the data. It really was - sticks out like a sore thumb.
But your computers do exactly what you tell them to do.
BOYAJIAN: And we would not have found it without, you know, human eyes seeing it and saying, oh, wow, that's interesting.
RAZ: So science is more often than not about raising more questions than finding answers. And it seems like in this case, you still don't know what's going on.
RAZ: Which is pretty cool.
BOYAJIAN: I don't know what's going on. But, yeah, but we're working at it, you know? We're collecting more data and, you know, we'll be able to rule out some things. And we'll be able to, you know, hopefully, you know, build evidence to support, you know, new hypotheses. But, yeah, we're still working on it. And there's a lot of people working on it, too.
RAZ: That's something to be proud of. I'm not - in no way am I disparaging that. That is great. There are more questions now than you can answer, which is better - which is great.
BOYAJIAN: Well, that's - yeah. That's science.
BOYAJIAN: That's right.
RAZ: Tabetha Boyajian, she's a professor of astronomy at Louisiana State University. You can see her full talk at ted.com. On the show today, Citizen Science. I'm Guy Raz, and you're listening to the TED Radio Hour from NPR. Transcript provided by NPR, Copyright NPR.