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You might not know astronomer Mike Brown, but you probably know his work.

They call me the Pluto killer because I killed Pluto.

I really feel like Pluto killed itself, but I was there and helped it along its way.

Mike didn't start out trying to murder planets.

As a kid, he actually loved Pluto.

How could you not love something like that?

It was this fragile looking little world that nobody really knew anything about.

As luck would have it, right when his career got going in the 90s,

tons of objects were being found out in the Kuiper Belt.

This region where Pluto is out past Neptune.

So I spent a number of years scanning the skies, searching and searching for big things out there

and really the straw that kind of broke Pluto's back was the discovery of Eris.

Eris is an icy world, a lot like Pluto, and it's pretty much the same size as Pluto.

So either Eris had to become a planet or Pluto had to become a non-planet.

But if Eris became a planet and Pluto stayed a planet, there were a bunch of other things that would have to become planets.

As much as I would have loved to be able to say, I found a planet, I found Eris, it's a planet.

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