From the Department of Interestingness
Saw a tweet about what "could be this year's biggest discovery" an almost entirely intact Roman mosaic villa floor:
My wife and I were wondering how that gets covered with so much dirt over the years. I dug down into this. Apparently, the soil in any given place absent of human activity grows about an inch a century.
But where does soil come from? Organic matter that does erode away is some of it, but here's something I didn't know: Rain exist because of dust particles in the atmosphere. The particles give something for the atoms in water to latch onto. Every time it rains a small layer of dirt is deposited on the ground. (I wonder if that's why my car is so dirty after it rains?)
I assumed all this dust just comes from the earth itself; kicked up in dust storms and what not. But here's possibly the most interesting thing you'll learn today: As much as 40,000 tons of space dust arrives on Earth every year.
That means that even planets made entirely of water would still have rain fall...though not as much as you think. The earth weighs 13,170,000,000,000,000,000,000,000 pounds and 40,000 tons is only something like 0.001% of the earth's mass. Our planet isn't really gaining mass at a significant rate, and a water planet probably isn't absorbing enough dust to make rain storms a common occurrence.
What is really cool about water planets is at their core is naturally occurring ice VII. Ice VII is, as I understand it, ice that has become crystalized so that it's indistinguishable from rocks. The only place scientist have found it naturally on earth is inside diamonds.
So...back to this Roman floor they found. How cool is that?
-Jake