Matt Kilty

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 Levitt 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 them 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.