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

we're asking 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.

This episode is sponsored by Audubble.

In the last decade alone, thousands of new planets have been discovered orbiting distant

alien suns, many of these far larger than our planet, called super-Earths.

But would these super-earths be superplaces for humanity to colonize and settle?

To my perpetual irritation, a lot of popular science articles tend to report every new exoplanet of

note with a great deal of hype, and one such

example is referring to super-earth-like in ways that imply we could move on to one tomorrow.

This tends to be justified by them being both Earth-like exoplanets we found, so I thought

for today we would discuss why that is, what super-Earthths are, if life could naturally evolve there and

get technological, and if we have any interest in colonizing them ourselves.

Now when I was a kid, planets numbered 9 and fell into two categories, rocky inner

planets and big gas giants, plus the Freak planet, Pluto.

Folks were always looking for Planet 10 or Planet X, which wasn't always being used as the

Roman numeral X or 10, and already debating if Pluto should count.

Indeed we had previously had more than 9 planets as we used to count the bigger asteroids

like Series and Vesta, and even before we found our

first exoplanes and the additional dwarf planets in our own solar system, there was a lot

of talk about how to reclassify planets.

...