Matt Kilty (21:29)
All right, it was incredible, but that was then and this is now. And if you are one of those people who still looks out across an ocean, you feel a sense of awe and wonder and a little bit of terror. Well, I'm sorry, but you're a child. I don't know what to tell you. It's really not that big of a deal. It's like a six hour flight to Europe, which is probably what you're looking at. That's it. And I mean, I don't know, to be fair, for like 300 years or whatever, this ocean was kind of like the biggest thing any of us could conceive of. There was nothing bigger until some very obsessive women came along. So around 1890, Boston, Harvard, every night a team of astronomers, all men, would sit in the Harvard Observatory and they would point an 11 foot long telescope into the night sky. And then they would open the shutter and the telescope on a clock driven mount would move in time with the rotation of the earth so that the faint light of the stars would stay fixed in relation to it. They would move at the same rate, telescope stars and lockstep together and for 30 minutes, maybe an hour, that faint light would come rushing down the telescope onto this glass plate, about the size of a notebook that was covered in this emulsion. The light would hit the plate, and slowly little dots would start to emerge. Stars, hundreds of them, thousands of them. Tiny little individual ones, big clusters of stars, all of them trapped within this glass plate. Think of it like a photograph of the night sky captured on the glass. The plate would then be marked with date and time and sent over across the street to. To this brick building that was full of computers. These are maybe people you've heard of, the Harvard computers. These are the women who were not allowed to work in the observatory because of the patriarchy. But they could go to this brick building where they were essentially computing the data, the data of the dots on the plate, the stars. So their job was to figure out, like, you know, the positions of the stars or if a star was actually a star or just like a speck of something or whatever. All of this was a part of our most significant attempt at cataloging the heavens. Now, one of these computers was a woman named Henrietta Leavitt. Got some fans in the house. So Leavitt started at the observatory at the age of 25. She was a former lit major who, her senior year, took an astronomy class and was just like, I think. I have no idea. She didn't write anything about what she experienced in that moment. But whatever it was, it had to be profound, because after that, for 30 cents an hour, she would go to this brick building, sit with about a dozen other women, and using a magnifying glass, she would study plate after plate after plate. And her job was to mark any star that she saw on these plates that were variable stars. What's a variable star? Great question, astute listener. So variable star is a star that, over time, varies in brightness. So some nights it appears a little bit dimmer. Some nights it appears a little bit brighter. This is just a thing that some stars do over the course of their life. So her job was basically to look for these dots on thousands of these glass plates that were getting lighter and darker and lighter and darker, and then circle them. Over the course of 28 years, she finds 2,400 of them. And that's it. That is her job. But it was in the midst of this, in the midst of these 28 years where something incredible happens. The thing that would shift our gaze, our deepest sense of awe and wonder as a species, from the sea to the stars. So Levitt's doing her job day in and day out when she comes across this one plate, a plate that contains the Magellanic Clouds, which is just like a cluster of stars close together that look like a cloud in the night sky. Now, this was crucial. Nobody knew how far that cloud was from Earth. In fact, we knew very little about how far anything was from Earth. We had an approximate distance to the sun, to the Moon, a few nearby stars, but that was pretty much it. Beyond that, we really had no idea, mainly because we didn't have a good way to measure anything in space. We didn't have, like, a yardstick. And so what we had settled on was this idea that everything in the night sky, all of it, was a part of our Milky Way galaxy, and that we here on Earth, we were floating in the center of the Milky Way, and that was the entire universe, us, right there in the center. But this plate was about to change that because Leavitt noticed this pattern, which was the bright stars, the bright variable stars that she was circling on this plate in the cluster. They varied really slowly. So it took him a long time to go from bright to dark, bright to dark. It was almost like uniform. So the brighter the star, the slower it would flicker. And she's like, oh, okay, there's a little pattern here. So she goes looking for it in the other stars in the cluster, and she finds, sure enough, that the dim stars, they varied more quickly. And this pattern, it was really reliable. So reliable, in fact, that one could use the time it takes for a star to flicker to just whoop on a graph, figure out the brightness of that star, which, I don't know, probably doesn't sound that important to anybody here. But this is a thing that would truly crack open the universe because. And this had always been the problem about figuring out distances in space. Like, let's say you're looking at a bright star in the night sky. Well, how do you know that bright star isn't just, like, really close to you or a dim star? Is that a star that's really far away, or is it just a dim star? Nobody knew how to answer these questions, but suddenly Leavitt could. The rate at which a star flickers tells you its intrinsic brightness. And once you figure out the brightness, with some fancy math, you can start to figure out distances. And so if we jump ahead 10 years after Leavitt plots out this pattern, publishes it in paper in the 1920s, Edwin Hubble is out in California with what was then the world's largest telescope, and he's pointing it up at another cluster of stars called the andromeda Cluster. And like I said at that time, people deeply believed that our entire universe was the Milky Way. But Hubble had suspected different. He just never had a way to prove it. And so there he is, pointing this incredible telescope up at the cluster. And in the cluster, he sees a few little flickering stars. So he watches one of them, this star called V1. And he watches it go from bright to dark, bright to dark, counts the number of days, grabs Leavitt's calculations, does a bunch of math, and he gets a number, an astonishing, unfathomable number. 900,000 light years away is that star from us, which is way outside of our Milky Way galaxy.
