Grant Ruthven, of Momona School, asks :-

How fast does the world travel?

Alan Gilmore, an astronomer at the Mt John University Observatory, responded.

The answer depends on what we measure the speed against.

The turning of the earth on its axis carries us around at 1200 km per hour in New Zealand. Places on the equator are moving even faster, though nobody notices.

The earth circles the sun at a speed of 30 km per second or 108,000 km per hour. At this speed it takes one year to do a lap around the sun. Then there is the movement of the solar system. The sun and planets, like a merry-go-round on a truck, circle around the centre of the galaxy. The galaxy is what we see as the milky way. It is a pancake-shaped cloud of hundreds of millions of stars of which our sun is just one. The combined gravity of all the stars keeps them moving in circles around the centre of the galaxy.

The sun and planets are moving along at about 200 km per second or 720 000 km per hour. It takes more than 200 million years for us to do one circle around the galaxy.

On top of that there is the movement of our galaxy, the sun and all the stars in the Milky Way. Our galaxy and its neighbours are moving at 600 km per second or 2 million km per hour. They are being pulled along by the gravity of a very large and distant cluster of galaxies dubbed 'The Great Attractor'.