DAVID GREENE, HOST:
Now is the moment in the program when I admit that I am a total Star Wars nut. Those of you with me, you might recall that Luke Skywalker's home planet of Tatooine enjoyed the warmth of not one but two suns. That dramatic scene, you remember Luke at dusk gazing at the weird peaceful sunset.
Well, anyway, there is a reason that we're talking about this. A new planet, a real one, called PH1 was just discovered and it has not two but four suns. And what's more, it wasn't discovered by a professional scientist. Instead, this new planet was found by amateur astronomers, so-called citizen scientists who were part of a network called Planet Hunters.
Joining us to talk about the discovery of PH1 and also the work of these armchair astronomers all over the world is Dr. Arfon Smith. He is one of the founders of Planet Hunters and the director of citizen science at the Adler Planetarium in Chicago.
Dr. Smith, welcome to the program.
DR. ARFON SMITH: Thank you. Thanks for having me on.
GREENE: I really can't wait to hear about this new planet with all these suns. But can you - I want to hear first about citizen science and this group you founded, Planet Hunters. Who are they?
SMITH: Sure. So Planet Hunters is one of our citizen science projects. These are projects where members of the public play a fundamental role in the sort of scientific process and discovery that goes on in science. And so this is our website. It's at PlanetHunters.org. And you can go online and basically look at data from a telescope. And we need your brain, your human intuition to interpret and analyze these data that are presented.
GREENE: So is it a matter of you're pumping out data and there just aren't enough eyes to look at it in kind of the professional science world, so you were looking for more people who were interested and excited about this?
SMITH: It really depends. I mean, there are tasks that need doing that are usually done by grad students but are not insanely difficult and can be achieved quite easily. And so we think that citizen science has a great place to play here, because these data sets are often beautiful to look at - maybe they're pictures of galaxies or something a little bit more abstract like in Planet Hunters.
But there are a lot of areas where human intuition and human interpretation is still far better than a machine can achieve. And so these are perfect candidate projects I think for citizen science.
GREENE: OK. And I'm just guessing here. PH1 must be named for Planet Hunters One, being the first planet that they found.
SMITH: It is. There was much kind of discussion within the group about whether we could name it after one of the authors. But the rules of International Astronomical Union state that you're not allowed to name planets after individual people.
GREENE: How is it possible for one planet to have four suns?
SMITH: That's a very good question and I wish I had a better answer for you. So what we know about this system is that there are two main stars here. There's something called an M dwarf, about half the mass of the sun, so this is called a red dwarf kind of planet. So quite a lot cooler than the sun. And then there's a star that's a little bit bigger than the sun, about one and a half times the mass of the sun, that's a little bit whiter, a little bit hotter.
And so Planet Hunters One is going around this pair of stars. But what's new about this one is of course there's actually another binary pair. It's about the distance between us and Pluto away. And I wish I could tell you exactly how this formed. Unfortunately, the models in which are developed currently to try and predict how planets form really don't support this kind of system.
GREENE: Can I get totally cliche for just a second?
SMITH: Of course. Is there life on PH1?
Probably not. Unfortunately, it's a bit hot. It's about 350 degrees on the surface.
GREENE: OK. That's hot.
SMITH: So there isn't liquid water on the surface. And currently the way that astronomers describe planetary candidates that might be Earth kind of analog - so places where life could exist - we usually say that we would want liquid water to exist on the surface. And it almost certainly doesn't in this case.
GREENE: That's Dr. Arfon Smith, who is director of citizen science at the Adler Planetarium in Chicago. We were talking to him about the discovery of PH1, a planet with four suns.
Dr. Smith, thanks for joining us.
SMITH: You're welcome. Thank you.
GREENE: This is NPR News. Transcript provided by NPR, Copyright National Public Radio.