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When a compass is not working

Source: licencja: CC 0.

Link to the lesson

Before you start you should know
  • how to determine cardinal directions using a compass;

  • that a compass is useless near the objects containing iron.

You will learn
  • to determine the cardinal directions with the help of a shadow;

  • to indicate the south direction with the pointer watch;

  • to determine the northern direction using the Polar Star;

  • to determine the cardinal directions by observing the surrounding nature.

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Nagranie dźwiękowe abstraktu.

How to determine cardinal directions with the help of a shadow?

In Poland, at noon, the Sun is on the southern side of the sky. During this time, the shadow cast by our silhouette or other objects is shortest and indicates the northern direction. When standing facing the shadow, it is easy to point the other directions. This method is effective only at a certain time – at noon.

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Determination of geographic directions using the shadow
Source: Andrzej Bogusz, licencja: CC BY 3.0.

How to find north at night?

The Polar StarPolar StarPolar Star in the Ursa Minor constellation will help us to determine cardinal directions at night. This constellation is also known in North America as a “Little Dipper”, and the North Pole can be found at the end of its “handle”. Its position in the sky remains virtually unchanged – it is located right in the north, on the extension of the Earth's axis. A characteristic and distinct Ursa Major constellation will help us to find it in the sky.

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Grafika przedstawia Gwiazdę Polarną należąca do gwiazdozbioru Małej Niedźwiedzicy, wyraźny gwiazdozbiór Wielkiego Wozu oraz Mały Wóz - Gwiazda Polarna znajduje się na końcu jego „dyszla”. Na grafice opisano: 1-To find the Polar Star, first we need to find the Ursa Major (”Big Dipper”) constellation, which is clearly visible in the sky. 2- Extend about five times the line from one of the bright stars that form the side of the bowl farthest away from the handle's tip to reach the Polar Star. 3- The Polar Star is located in the constellation of the Ursa Minor (“Little Dipper”) - at the end of its “handle”. The northern direction will be below the Polar Star.
Determining the direction using the Polar Star.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

Will the watch allow us to point south?

The southern direction can be determined with a pointer watch with a relatively high degree of accuracy. How to do this? First, set yourself so that a small pointer (hour one) points to the Sun. You do not even have to take off your watch - just hold your hand so the dial is placed horizontally. The line dividing the angle between the small pointer and 12:00 on the watch dial will indicate the south direction. Till noon, we take into account the angle between the small pointer and the left side of 12 o’clock, whilst after noon, the angle between the small pointer and the right side of 12 o’clock.

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Ilustracje przedstawiają wyznaczanie kierunków świata za pomocą zegarka. Na ilustracji z lewej zaprezentowano wyznaczanie kierunku południowego z użyciem zegarka wskazówkowego przed godziną dwunastą. Na ilustracji z prawej zaprezentowano wyznaczanie kierunku południowego z użyciem zegarka wskazówkowego, w godzinach przed szóstą i po osiemnastej.
Setting directions of the world
Source: Andrzej Bogusz, licencja: CC BY 3.0.

How does nature help determine the cardinal directions?

We can also try to determine geographical directions by observing the nature around us. It is, however, less accurate method. You should remember that in this way you will determine the cardinal directions only approximately.

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Moss on the north side of a tree
Source: www.flickr.com, licencja: CC BY-NC-ND 2.0.
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Exercise 1
Lidka, Marta and Marek talk about the methods of determining geographical directions when the compass is not working. Identify the person whose opinion is true. Możliwe odpowiedzi: 1. Marta: Geographical directions can be determined at noon with the help of a shade., 2. Marek: Geographical directions can be determined very precisely observing how the anthill is built., 3. Lidka: Geographical directions can be determined by observing the Moon.
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Exercise 2
Określ położenie: Gwiazdy Polarnej oraz konstelacji: Little Dipper and Big Dipper.
Source: licencja: CC 0.

Summary

  • Cardinal directions can be determined during the day with the help of a shadow or a pointer watch.

  • At night, the northern direction can be determined by searching for the Polar Star.

  • Cardinal directions can be determined with low accuracy by observing nature.

Keywords

Polar Star, cardinal direction, determining cardinal directions

Glossary

Polar Star
Polar Star
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Nagranie dźwiękowe słówka.

Gwiazda Polarna – gwiazda z gwiazdozbioru Małego Wozu, znajdująca się blisko przedłużenia osi Ziemi i niemal niezmieniająca swego położenia na niebie; dzięki niej odnajdujemy nocą kierunek północny