Matt Kilty

And she's like, oh, OK, 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.

And so he watches one of them, the star called V1.

And he watches it go from bright to dark, bright to dark.

Counts the number of days, grabs Levitt's calculations, does a bunch of math, and he gets a number.