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.

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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-earths as Earth-like in ways that imply we could move on to one tomorrow.

This tends to be justified by them being both Earth-like exoplanes we found,

so I thought for today we would discuss why that is, what super-earths 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 nine 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 nine planets, as we

used to count the bigger asteroids like Series and Vesta, and even before we found our first

exoplanets and the additional dwarf planets in our own solar system, there was a lot of talk

about how to reclassify planets.

We knew that our catalog would expand enormously and that we would doubtless find thousands

...