Question #3 What Does e=mc2 Really mean?

Ah yes, e=mc2. Albert Einsteins theory of relativity. OK, lets stop right there. e=mc2 is not the theory of relativity. e=mc2 is a mass-energy equivalence equation that was used in one of the many papers published by Albert Einstein over a period of time on his theory of relativity that he was developing. The equation e=mc2 did not in fact appear at all in Einsteins first paper on mass-energy equivalence. It was written as a sentence "if a body gives off the energy L in the form of radiation, its mass diminishes by L/V².". Except it was in German. The formula went through many iterations by other scientists before Einstein refined it in 1946. To see where this equation fits into his theory of relativity though you need to know the full formula. 
Find out after the jump....

Question #4. Why is water wet?

Why is water wet? A question posed to me by my son quite some time ago. The only answer I could offer at the time that wouldn't completely bemuse him was that water is a fluid and if the water was dry it wouldn't be very good water. It was a good enough answer at the time.

Question #5. Where did the Moon come from?

This is a good one. I really enjoy the mental imagery that comes along with this.
There are a few theories for this one but there is only one that makes sense to me and I honestly don't understand how the other theories can have any amount of support if they are being considered rationally. One theory is that the Moon formed independently of Earth in an Earth orbit during the formation of the solar system, another is that the Moon formed independently of Earth elsewhere in the solar system its formation and was captured by Earths gravity well and settled into a stable orbit. I don't subscribe to either of these theories.

Question #7 - How many things are there in the solar system?

The Solar System. Start counting!

When I was at school the solar system consisted of the sun and 9 planets. The third planet had a moon, so that was 11 things. And if that was it, this would be so much easier, but it's not. There aren't even 9 planets any more, there are 8. The ninth planet was demoted to dwarf planet status and several other dwarf planets have been discovered since then. There are comets, asteroids, moons/satellites and of course the things that we have put out there.