Zoe Harris, of Balclutha Primary School, asks :-

Why is there a boy planet (Mars) and a girl planet (Venus)?

Pam Kilmartin, an astronomer at the University of Canterbury's Mt John Observatory, responded.

There are no boy planets or girl planets. Planets just are planets, lumps of matter which move around our Sun.

But when humans try to understand what the world around them, or the universe around them, is all about, we tend to talk about things as if they were people. So, a few thousand years ago, the Greeks gave the names of their gods to the 'wandering' stars, that is, the planets. I don't know exactly when or how it happened, but the Greek names for the planets were replaced by the Latin equivalents and these are what we use today. They could see five: Mercury, Venus, Mars, Jupiter and Saturn. The others, Uranus, Neptune and Pluto, and the minor planets, were not discovered until relatively recently, but the same kind of names were given to them.

The early astronomers, who were also astrologers, used symbols to represent the planets on their diagrams. For example, Jupiter's symbol is a stylised thunderbolt, Mars has a circle with an arrow because Mars is the god of war, and Venus has a circle with a cross beneath representing a mirror for she is the goddess of love. At some time, these two symbols for Mars and Venus were taken over by biologists, to mean male and female. These meanings have been transferred back to the planets themselves in the popular imagination.

But the names we give the planets are just convenient handles, and have nothing to do with the nature of the planets themselves.