It’s a small world after all, at least if you measure it vertically.

The crust of the earth on our little planet is between 3 and 44 miles thick.

The atmosphere … it’s harder to say, but one measure called the Kármán line is a little over 60 miles measured from the surface, to the start of space.

So the habitable zone of all life as we know it anywhere is this thin strip on and above and below this surface, less than 100 miles. Measured vertically.

Even that’s generous, because although life can theoretically exist at extreme temperatures down close to the mantle, or way far up in the outer reaches of the atmosphere, most life doesn’t.

It instead exists in an even narrower band, closer up or down to the part we stand on. A band smaller than the average Sunday drive. Maybe still miles, but maybe miles measured in the single digits.

I learned this starting here, and doing a little researching over and above.

Bonus fact.

At any given moment, tens of millions of tons of diamond hail is falling down toward the interior of Saturn. As it gets warmer and closer to what passes for the surface of the planet, it melts into diamond rain.

I never thought about diamond rain before.