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.

Oh.

Series A itself is the brightest star in our night sky, and about 25 times as luminous as the sun,

which puts its habitable zone centered around 5AU closer than we think.

Even before we built our first crude spaceships, Alpha Centauri has loomed large in our

imagination as the gateway to the stars.

It's the closest system, the one every science fiction writer sets their sights on, and

our recent episode, the first interstellar colony mission, we consider the Alpha Centauri

System, along with Proxima Centauri, as high probability candidates

for first missions.

While maybe our first, it certainly won't be our last.

There are, after all, a few hundred billion stars in this galaxy alone.

Beyond Alpha Centauri lies an entire neighborhood of stars.

Dim red dwarfs, ancient suns,

white dwarfs coolly in the dark, and even the faint glow of failed stars that never

quite ignited.

Within just a dozen light years, there are more than a dozen systems.

Stretching out to 25 light years, we find a tapestry of K, G, and F-type stars that could sustain human industry

and offer decent terraforming prospects, and even stars far smaller than our own, such as Red

...