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.nebula.tv slash Isaac Arthur and use my code, Isaac Arthur.

The interstellar void is deep and black as eternity, but scattered through it are worlds that

burn with their own quiet fire. Not every world needs a sun to shine. In the vast reaches

between stars, a strange kind of world drifts alone, unlit, unanchored, and untethered to any sun.

These are the rogue planets, wanderers of the void, cast adrift through cosmic misfortune, or possibly born that way, in the cold, interstellar wilderness.

Today, we are returning to a topic we explored years ago,

with sharper eyes and broader horizons. Back then, we considered rogue planets mostly as a

curiosity, a scientific puzzle or a doomsday hypothetical, but a lot has changed since then.

Not only have we learned more about how common these worlds might be, we've also

deepened our understanding of how life might survive on them, and how we might one day call them

home. This is outward bound, our series on how humanity might colonize the toughest, weirdest,

and most extreme places in the cosmos, and rogue planets might just take the

crown. No light, no sunrises, no seasons, just a frozen sky, and whatever warmth you can bring

with you, or dig down to find. In the interstellar night, warmth is a treasure, and pressure is

life.

Survival doesn't begin with oxygen or sunlight. It starts with shelter from the void,

enough energy to keep the blood moving and the machines humming. But even in the deepest dark,

possibility is persist. Some of these worlds may harbor hidden oceans, warmed by internal

fires, or thick atmospheres

...