Chapter 1: What is the main topic discussed in this episode?
In the military, transgender troops face a new crackdown. Like in my head, I know I'm doing nothing wrong. I feel like I'm hiding something, but I shouldn't have to hide it. On the Sunday story, how the Trump administration is pushing out trans service members and what this could mean for mission readiness. The Sunday story from the Up First podcast. Listen now on the NPR app.
You're listening to Shortwave from NPR. Hey, Shore Wavers. Regina Barber here. Recently, our producer, Burleigh McCoy, was out on a frozen lake near her home. It's been a weird winter, so I was already kind of worried about the ice safety. Don't worry. Burleigh knows about being safe on the ice. But then she saw something that freaked her out.
There were these like star-looking kind of spidery patterns in the ice. They were black and branching, and they kind of just made me nervous because I spent a lot of time on the ice, and I hadn't seen them before, and I didn't know what they were. Lucky for Burley, she works on a science podcast. So we called up an expert to ask about this icy phenomenon.
They're actually quite common, but you need a particular set of circumstances to happen. Victor Tsai is a geophysicist at Brown University. He says the thing Burley was seeing is called a lake star. He studied them as a visiting graduate student at Woods Hole Oceanographic Institution. There, his advisor gave him a task. Figure out the science behind lake stars.
Victor did, by creating them in the lab. And here's the cool thing. The research eventually led Victor somewhere unexpected. A water world in space. Today on the show, lake stars. How they're formed, and why studying them may help us understand where the water is on Europa, one of Jupiter's largest moons. We'll also tell you, and Burleigh, what Lake Stars might say about the safety of the ice.
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Chapter 2: What are lake stars and why are they a mystery?
You're listening to Shortwave, the science podcast from NPR. In the military, transgender troops face a new crackdown. Like in my head, I know I'm doing nothing wrong. I feel like I'm hiding something, but I shouldn't have to hide it. On the Sunday story, how the Trump administration is pushing out trans service members and what this could mean for mission readiness.
The Sunday story from the Up First podcast. Listen now on the NPR app. Let's start with a little Lake Star Science 101 with geophysicist Victor Tsai. The basic idea is just that there's a thin layer of ice with some snow on top of it. The snow pushes down on the ice.
At the same time, if a small hole forms on the underside of that ice... That allows warm lake water to seep up through that hole and then melt through this slushy snow layer and eventually form these star patterns. When all these things happen, you get a lake star. But Victor wanted to actually figure out the math and physics behind this process.
In our conversation, Victor told me field work wasn't possible. It was summer when he was working at Woods Hole. So what we decided to do was to go into a cold lab and create our own miniature lake stars by forming slushy ice on top of a cold surface and then pour relatively warm, just barely above freezing water through that slushy ice. So how did you make this slush ice?
So the lab didn't have a way of producing this slushy, snowy layer. And so I purchased a blender. And one of the challenges is trying to make a slushy snow that's similar to what you can find in nature. But I found that playing around with different blender settings and things like that, I could make a slush that was similar to what we observed. Wow, that is really, really cool.
So you had like different kinds of slushies. Did you actually make like drink slushies and like drink them and stuff? I did. Although not at the same time. Because, you know, it's very cold in the cold lab. Yeah, you don't want it in there. But it was the summer, you know? It was. So you like basically have this like...
flat surface and you put this fun slushy stuff from your blender on top and then you said you drip water how fast do you have to drip it like how much water is going in and then what do you see after that happens Yeah, we have to drip the water relatively slowly so that it's a sort of constant flow that doesn't... Like a leaky faucet.
Yeah, like a leaky faucet so that it doesn't catastrophically break up this slushy layer. And then basically what you observe is that first you start with a little drip and so you have a sort of circular melt pattern. But then as it spreads out, you start to get these star-like patterns forming with these arms where you are melted. Let's say you wanted to do this at home.
What could people do to try to make their own lake stars? Yeah, you can certainly make your own. You can do exactly what I did. Take a kitchen blender, form some slush, place it on a flat surface, and then try to pour some slightly warm water through that slush pattern. Slightly warm, like room temperature? Yeah.
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Chapter 3: How do lake stars form according to geophysicist Victor Tsai?
OK, OK. Coming back to like lake stars on Earth, let's let's we were in space for so long. Let's come back to Earth. I know a lot of people actually live around frozen lakes. One of our producers, Burley, does the presence of lake stars like you see them, you maybe could walk on top of them. Does it indicate that it might not be safe to to like walk over those those lake stars? Yeah.
So or in the ice in the area? Right. So if a lake star had recently formed, then it would be very not safe. Okay. Because that means that the ice was very thin and then there's mostly snow and slush on top of that. And it probably would not be able to support your weight. So if it had just formed, then you can still see the kind of snow on top.
But in many cases, you get very thick ice forming afterwards that preserves the lake star's. And so actually most of the cases where people have observed them are in cases where there's thicker ice. And sometimes people have been walking on that thicker ice and then see the lake stars there. So basically, if you see one, wait a couple days, then don't go over there until it's been a couple days.
Okay. All right. Victor, thank you so much for talking with me today about lake stars. I've never seen one. Now I'm going to be looking. Great. Yeah, sure. No problem. If you like this episode, we have a request. Please share it with a friend. It really helps our show out. Also, check out our series about lake ice loss and what it means for community, cultures, ecosystems, and safety.
This episode was produced by Burleigh McCoy, edited by Viet Le, and fact-checked by Tyler Jones. The audio engineer was Jimmy Keeley. I'm Regina Barber. Thank you for listening to Shorewave from NPR. In the military, transgender troops face a new crackdown. Like in my head, I know I'm doing nothing wrong. I feel like I'm hiding something, but I shouldn't have to hide it.
On the Sunday Story, how the Trump administration is pushing out trans service members and what this could mean for mission readiness. The Sunday Story from the Up First podcast. Listen now on the NPR app.
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