A Cool Star Yields The Most Earth-Like Exoplanet Yet

7:13 minutes

three sunsets, side by side. the leftmost is of the earth. the second, a simulation of exoplanet teegarden b, is double the size. the rightmost, a simulation from the potential exoplanet teegarden c, is about the same size as earth's
A simulation of sunsets from the potential exoplanets around Teegarden’s Star, as compared with Earth. Credit: PHL @UPR Arecibo.

A nearby red dwarf known as Teegarden’s Star may be the home to the most Earth-like exoplanet yet found, according to new data from the Spain-based CARMENES survey for exoplanets. At a mere 9 percent of the sun’s mass, Teegarden’s Star is cooler than most stars—but one of its planets appears to have the highest Earth Similarity Index of any exoplanet yet discovered.

Gizmodo staff writer Ryan Mandelbaum joins Ira to explain why Teegarden b is exciting news in the world of exoplanets, though also a place of  many unknowns. Plus, the first known fossil of a narwhal-beluga hybrid, a Norwegian town that wants to live without time, and San Francisco’s stance against e-cigarettes.  

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Segment Guests

Ryan Mandelbaum

Ryan Mandelbaum is a science writer and birder based in Brooklyn, New York.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. A little bit later in the hour, dogs. They have been evolving alongside the humans for thousands of years. And not only have they become friendlier and more dependent on people, they’ve even developed a secret weapon to manipulate us– their puppy dog eyes. You know what I’m talking about. And we’re going to talk about that a little bit later. 

But first, scientists searching for planets in other solar systems have done it again. They have found the most Earth-like exoplanet to date, according to something called the Earth Similarity Index. Here to explain why planet hunters are looking so hard at small, cool stars, plus others like [INAUDIBLE] subjects in sciences, Gizmodo staff writer Ryan Mandelbaum. Always good to have you. 

RYAN MANDELBAUM: Always great to be here, Ira. How are you doing? 

IRA FLATOW: Let’s talk about this planet. How can we know it’s actually Earth-like? 

RYAN MANDELBAUM: Well, so this is around Teegarden’s Star. Scientists were able to find this planet in a survey. It has an orbit of approximately 4.91 days. The other star’s around 11.4 days. And the way that you determine if it’s Earth-like is if it kind of looks like Earth in how big it is and how much it weighs, and if it’s in the part around the star where the temperature would be nice. 

IRA FLATOW: Sounds like a duck. Well, so is there really an Earth Similarity Index that it passes, that you have to check off all those boxes? 

RYAN MANDELBAUM: Yeah. I mean, the Earth Similarity Index is something scientists use basically to determine how close an exoplanet is to the Earth. But of course, that comes with the caveat that it doesn’t take into account how the star might affect the planet’s atmosphere. So just because a planet might have 70 degree Fahrenheit temperatures doesn’t mean that it’s actually going to be a habitable planet. 

IRA FLATOW: So this star is small and cold. Is that the new thing now, looking for a cold one? 

RYAN MANDELBAUM: Well, if we could find an Earth-like planet, I don’t think we care what star it’s around. But these red dwarf stars have just proven to be a host of these Earth-like planets. Even Proxima Centauri, our closest neighbor, seems to have an Earth-like exoplanet around it. And so this is just a really great way to look for these stars and a really great sort of direction to go. 

IRA FLATOW: And just to be clear, this exoplanet was not found by the Kepler Mission, right? 

RYAN MANDELBAUM: No, no, this is the CARMENES telescope in Spain. 

IRA FLATOW: OK, let’s go back to Earth a little bit. A village in Norway– this is amazing– wants to live without time. How would that work? 

RYAN MANDELBAUM: I’ve been trying to figure that out myself. So I spoke to the guy behind it, Kjell Ove Hveding. And what he said– in this town of Sommaroy, they want to get rid of clocks. And that’s because they live north of the Arctic Circle, so the sun doesn’t rise every day. The sun rises once a year, and it sets once a year. And so he had this idea. Everybody’s so caught up in their schedules, and we don’t make time for anybody anymore. So let’s just get rid of the clocks. In the middle of the night, you can go gardening at 4:00 AM there. So he thought, why don’t we just do that? 

IRA FLATOW: Yeah, when I was in Antarctica, where it was six months of daylight, that’s what people did. They were going at 11 o’clock at night. They started doing things. But when you’re in Antarctica, you’re not really doing commerce or business, where you have to pay attention to the clock. How do they deal with that? 

RYAN MANDELBAUM: Well, Ira, we live in a society that relies on clocks. So it doesn’t work so well. Kjell and I, when we were speaking, he said I only have 20 minutes because he had to go catch a plane. And you can’t catch a plane if you don’t have a clock. But the other thing is that scientifically, that probably wouldn’t work out so well. We evolved in a place with 24 hour cycles. 

IRA FLATOW: And we have circadian rhythms, right? 

RYAN MANDELBAUM: Exactly. And all sorts of things rely on the circadian rhythm– I mean, our sleep cycles, our hormonal cycles. We have body temperature, gastrointestinal tract. I mean, it is important to maintain a rhythm. 

IRA FLATOW: But even so, there are people who live in almost total dark– in the Arctic Circle, total darkness in the winter time. How do they know– what happens to their circadian rhythm? We ought to look into that, yeah? 

RYAN MANDELBAUM: I think there was research of a guy who lived in a cave for a long time. And he still maintained approximately– not exactly– but approximately a 24 hour calendar, schedule. 

IRA FLATOW: Let’s get out of the cave and look at, well, maybe a strange skull– get to this strange skull that is finally identified. And what is it? 

RYAN MANDELBAUM: Oh, I love this. It’s a hybrid between a narwhal and a beluga. So these two arctic cetaceans, some time in the ’80s, the hunters came across this strange animal. It had a beluga’s flipper, a narwhal’s tail, and they killed it. They gave the skull to some scientists. And now DNA evidence has indeed revealed that the skull was a hybrid between a narwhal and a beluga. I mean, it’s crazy. 

IRA FLATOW: So you can have that happen. They can be a hybrid. 

RYAN MANDELBAUM: Yeah, in fact, cetaceans, like whales, they do it. They hybrid with one another. And we don’t know exactly what happened. But we do know that the beluga was the male. The narwhal was the female. And the two species have been seen traveling in pods with one another. So what probably happened was a– they say a young male beluga probably got caught up with a big pod of narwhals. And one of the female narwhals allowed him to be the father. 

IRA FLATOW: And then this skull has been sitting on somebody’s desk or on their shelf for decades? 

RYAN MANDELBAUM: That’s right. Well, it’s been long hypothesized to be this hybrid. Because if you look at it, it really does look like a beluga, sort of. They have regular teeth. Narwhals have these long, single tooth horns. And its teeth are splayed outwards, almost like a cross between a beluga and a narwhal. But it lived to be an adult. So it clearly did fine. 

IRA FLATOW: Is this– how shall I put– potentially bad news? Especially climate change brings narwhals and belugas closer together. 

RYAN MANDELBAUM: Sure, the study authors did tell me that this seems to be a one off case. We don’t know. Hybrids generally could be bad news because if a rare species doesn’t find a mate, then they pick some other species, and they produce unfit offspring. And that’s obviously bad. 

IRA FLATOW: Finally San Francisco wants to make a statement about e-cigarettes. 

RYAN MANDELBAUM: San Francisco is poised to be the first city in the United States to ban e-cigarettes, or at least until the FDA will review e-cigarettes. It’s an interesting situation. You might know that vaping is really popular among teens right now. I think it’s one in five teens have said that they use these e-cigarettes. And it’s been called one of the country’s biggest public health challenges. Now, will this work? We don’t know. 

IRA FLATOW: Well, watch out. As they say, as goes California, so goes the nation. 

RYAN MANDELBAUM: Right, yeah. And what’s interesting is that Juul, the industry leading e-cigarette company, is actually based in San Francisco. They’re partially owned by the tobacco giant Altria. So obviously, they’re not happy with this. And they’re trying to fight the base, but you know. 

IRA FLATOW: Oh, yeah, that’s interesting. That is interesting. We’ll pay attention. Thank you, Ryan. 

RYAN MANDELBAUM: Thanks so much for having me, Ira. 

IRA FLATOW: Ryan Mandelbaum, staff writer at Gizmodo here in New York.

Meet the Producers and Host

About Christie Taylor

Christie Taylor was a producer for Science Friday. Her days involved diligent research, too many phone calls for an introvert, and asking scientists if they have any audio of that narwhal heartbeat.

About Ira Flatow

Ira Flatow is the host and executive producer of Science FridayHis green thumb has revived many an office plant at death’s door.

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