1) I asked this of a world renowned physicist and SETI's main radio astronomer within the last couple of months. They both said no, just a scratch, and there would even be enough of the human population left to continue the existence of the human race. There would be areas where it would be safe to live. Gradually the air in the worst affected parts of the planet would once again be fit to breathe. Whenever I hear the Greens say that something would be bad for the planet I cringe. What they really mean is that it would be bad for human beings, animals etc which could all be wiped out. But the planet would go on as ever. In the various cataclysm scenarios some tiny organisms would survive, maybe deep underground and evolution would begin again. In the 4.5 billion years of the Earth's existence there have been at least four cataclysmic events, two of them wiping out 95% of all life. The dinosaurs were in charge for 250 million years, then the asteroid crashed and made life impossible for all but the tiniest of creatures. Evolution began again and thus we are here. If the asteroid had not crashed into the Earth it is likely that the dinosaurs would still be in charge and we would not exist.


2) Our Sun is a star. Nearly all stars have planets orbiting them. In fact we have yet to discover a star that has no planets. Our Sun provides light and heat to the planets which orbit it. Earth turns on its axis once per 24 hours. At night in the UK we are facing away from the Sun. The planets whose orbits are nearest the Sun are the warmest. Thus Mercury is very hot and Neptune is very cold. A moon is a body that orbits a planet. Earth has one moon. Jupiter has 79 and Saturn has 82. Yes, some moons are bigger than some planets but this relative size is of no consequence to the definitions of moon and planet. A planet orbits a star, such as the Earth orbits our Sun. A moon orbits a planet such as our Moon orbits the Earth.

3) I do not know.

4) Maybe make-up, clothes, the respective dates these series were made and the character's personality are all in play here.