Hello Explorer, welcome along. I hope you're ready for an adventure because it's time to search through the solar system.

Should we see what's waiting for us in a brand new science quest?

My name is Dan and twice a week we are here exploring our awesome galaxy and a bit further beyond too.

We'll search outloads to science secrets, discover deadly beasts, chat to absolute geniuses as well.

So it's all about discovery.

And, well, this episode, it's about discovering the answers to your questions.

If you ever have anything scientificy that you want answered that you need sorted,

make sure you leave it as a voice note for me on the free FunKids app and at FunKidsLive.com.

It's seriously so easy.

Just a few buttons, click the big red one on the app, and it will come straight through to me and I can do the digging.

First one this week, it's from Alfie.

My name is Alfie, and I'm seven years old, and I live in fruit.

And my question is, what is the hardest thing on Earth?

What is the hardest substance on Earth?

Well, could it be Lonsdalate?

A rare mineral formed when graphite-rich meteors hit Earth from outer space?

We don't think so. Could it be Vertite boron nitride? Something created during volcanic eruptions that's made of loads of different elements?

No. Scientists think that it is diamonds. Diamonds are made of one single element, carbon.

Deep underground, that carbon has broken down through millions of years of dead things, really,

decomposing creatures and plants.

It gets squashed down, squash, squash, deep underground into so much pressure that it forces that carbon into a very specific structure which is incredibly hard. Technically,

diamonds are properly unbreakable. They are a little bit, I guess, because you can still

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