1. What's at the Earth's core?
A solid ball of iron the size of the moon.
2. Why do we sleep?
The brain has to idle and we have to rest.
3. What is the universe made of?
Everything in existence plus other "stuff" that we have not yet discovered.
4. Will forests slow global warming - or speed it up?
The answer will depend on which insects eat the leaves. We have to know what lives in the
forest to predict what will happen to global warming.