IMO The great size.

Delightful!

We probably don't even know the answer to this question yet.

Like ive said - we are stardust - the most amazing thing to me is how DNA strands started forming

Another take is how many stars had to go supernova in order to produce the amount of heavier elements now present.

Our planet may be called 'Planet Hell' by other denizens of the universe. We need oxygen to survive, oxygen which corrodes metals, turning iron to rust and breaking it into smaller and smaller pieces until you are left with iron ore, and reacts to most substances. We need water also, sometimes called a unversal solvent because so many things will dissolve in it (sounds like an extreme acid or base). So we need these two substances, which are highly reactive, in order to live. ET may take a look and say WTF?

I heard this a few times before not sure if it was on here, I don't think so. But Neil is always good to listen to.