Ambitexto

The Moon is 400,000 km away. How does it lift the sea 12 metres?

• Near Bristol, the sea rises and falls by more than 12 metres.
• The Moon pulls the far side of the Earth least, yet the sea bulges there too.
• The Bristol Channel is a funnel tuned to the rhythm of the tide.

A tide table is the Moon's timetable, and it has never once been cancelled.

Words for the text

tide

The sea coming in and going out, usually twice a day.

gravity

The force that pulls things towards each other.

bulge

A round part that sticks out.

high tide

When the sea is at its highest point.

low tide

When the sea is at its lowest point.

The opening of the text

In and out

The Moon is nearly 400,000 kilometres away. Yet twice a day it moves the sea, and near Bristol the sea rises and falls by more than 12 metres. Sit on a beach in Britain for an afternoon and you can see it happen. When you arrive, the sea is far away, behind a wide stretch of wet sand. Two hours later, it is near your towel. Nobody pushed it. It just came in.

Then, slowly, it goes back out again. This happens every day, on every coast. We call it the tide. When the water is at its highest, it is high tide. When it is at its lowest, it is low tide. The difference in height between the two is the tidal range.