Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asked at the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content, check out

go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

The solar system has a way of reminding us that it isn't finished giving up its secrets.

Early of the summer, astronomers announced the official discovery of a new dwarf planet,

over 400 miles wide or about 700 kilometers.

That's around the size of Germany, and it's on an orbit that swings from

the outer Kuiper Belt all the way out to over 1,600 astronomical units. So far, there's

a year lasts some 25,000 Earth years. For the moment, it holds the uninspiring name of

2017 OF 201, which just refers to when the possible minor planet got spotted for the first time.

Now that it's been confirmed and is a probable dwarf planet, like Pluto, not just a minor

planet, it is likely to get something more interesting as a designator.

But is it an interesting place?

To the casual eye, it's not a lump of ice, but to a civilization

thinking in terms of megastructures and interstellar journeys, this is no mere iceball. It's a

potential waystation to the stars, a seat of dozens of Earth's worth of living space,

and a reminder that the crumbs of the solar system are still

vast enough to feed empires.

What Counts as a Dwarf Planet?

Pluto's so-called demotion in 2006 remains one most controversial decisions in astronomy,

and, in my mind, one of the silliest

...