Last month, I got a little excited because I discovered Tolar wasn’t possible where it was. Its orbital period – 2.03 Earth years – was too long to be in the habitable zone of its star, Beta Hydri.

Turns out I had mis-copied the equation. I was using a simplified equation that expresses the relationship between the star’s mass, the planet’s distance from the star in astronomical units, and the orbital period. What I wrote was that the star’s mass is related to the square of the planet’s distance divided by the square of the orbital period. This puts Tolar out in the cold. It should be a frozen ball of ice.

But no. My old eyes had turned a 3 into a 2 — it’s the cube of the planet’s distance.

Don’t panic. I won’t subject you to any more math. But trust me when I say it makes all the difference in the world. The proper equation puts Tolar near the edge but still inside Beta Hydri’s habitable zone.

Water flows. People can go outside without turning into popsicles.

*phew*

I also did a few more calculations, because I was worried about the sun’s apparent size in the sky. I got another dose of relief: if I did the math correctly, Beta Hydri’s angular size is about 32 arc minutes. The sun seen from Earth is about 30 arc minutes. So – we’re good. And I’m happy.