Ciência Viva

The nocturnal

As it is impossible to tell the time from a sundial at night.

Using the nocturnal the navigators looked at the North Star and were able to tell the time. They could only do this at night. During the day they used the sundial.

When you look at the night sky, the North Star always shows the north of the Earth. The other stars all revolve around the North Star.

Make your own nocturnal.

Cut out the two wheels and the pointer with a scissors.

Make a hole through the black dots on the wheels and the pointer.

Put the two wheels and the pointer together, line up the holes and push a small straw through the hole.

Your nocturnal should look like this:

Now you can try out your nocturnal.

Turn the small wheel so that the pointer shows today’s date, e.g. if it is the 26th March, the pointer should be in the position shown below.

Take the nocturnal and point it towards the Little Dipper so that you can see the North Star through the hole. Always keep the handle pointing downwards.

Turn the large pointer until you can see the Kochab Star. Look at the time shown by the small wheel of the nocturnal.

At night, the Little Dipper and the other stars in the sky all revolve around the North Star.

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