Katie Arnott, of Greymouth Junior High School, asks :-

How did Stars and Planets come to be?

Gerry Gilmore, a New Zealand astronomer now based at Cambridge University in England and who uses enormous telescopes in Hawaii, Chile and Australia to examine such questions, responded.

It all started with the Big Bang, which happened about 15 thousand, million years ago.

After the Big Bang everything in the Universe was made from hydrogen gas or from helium gas. Nothing else. It was extremely hot, and expanding rapidly. So things rushed away from each other just as fast as they could, cooling down a bit as they did. Eventually the hot gas cooled enough that it could form into clouds, and these in turn could cool some more.

Some of the large clouds got so big they were too heavy to stay as clouds so they started to collapse and eventually formed a star.

Planets are made from the junk left over after the star has formed. Some of this junk can sometimes collect into a ring of dust and molecules, which move round the new star. If there is enough of this stuff left it can be attracted into larger and larger lumps until a big enough piece forms so that it will survive being blown away by the new star. Then we call it a planet.

Actually there are probably a few more complicated things happening too, which I haven't told you about since I don't understand them. No-one else does either. Maybe you can discover the answers when you are older? Its great fun trying!