Spatial orientation with compasses, maps, GPS, and stars

Maria took a wrong turn while hiking and now… she’s lost! To get back, she needs to first figure out where she is. What are some tools Maria can use to orient herself in the landscape? Maybe using a compass will help. Every compass has the same basic parts.

On its base are the four cardinal directions: north, south, east and west, often marked by single letters. In the middle, there is a needle, which is actually a small magnet. The Earth's magnetic North Pole "pulls" at one end of the magnetic needle. That end always points to the magnetic North Pole, no matter how you twist the compass. To make use of the compass, Maria needs to put it flat and level, and then rotate it until the red coloured tip or arrow of the needle points to N, which stands for north.

This will show her the direction of magnetic north. This is not really enough to help Maria. Luckily, she also has a map. A map shows a much smaller version of the world or an area. How much smaller?

Well, that depends! Maps usually have a scale to help you compare the distance on the map to the distance in reality. Paper maps mostly rely on symbols, colours, and different lines to represent features that are physically seen on land. To learn what these different symbols mean, find the map’s legend. Try comparing features on the map to the features you see around you, Maria.

Look for big features like mountains first, then look at smaller details, like rivers. On paper maps, the top of the map is almost always north. You can use your compass to help align your map so that north on the map corresponds to north where you are. Nowadays, digital maps are available on the internet. It can be a bit easier to read a digital map, since they do not rely on symbols and instead show real representations of objects.

Today, many people use a Global Positioning System, or GPS, to help them find their location on digital maps. GPS relies on over 30 satellites that are located in space and constantly send out signals. GPS receivers can show your exact position on a map at any particular location, and trace your path across a map as you move. But what if Maria has no compass… no map… no GPS… can she still orient herself in the landscape? Yes!

Just look up! For thousands of years, people have used the stars in the sky as a way of navigating. You can do it too, with just your eyes and a dark sky. In the Northern Hemisphere, the most useful star for navigation is the North Star, Polaris. First, find this part of the largest constellation in the Northern Hemisphere Ursa Major.

It has a distinctive shape that looks like a kitchen ladle or a plough! The two outermost stars, farthest from the “handle,” point to Polaris! Polaris is located at the tip of the constellation Ursa Minor and it is very bright. Follow the pointers in a line until you reach Polaris. No matter where you are in the Northern Hemisphere, once you're facing toward Polaris, you're facing north!

In the Southern Hemisphere, Crux, commonly known as the Southern Cross, is your point of reference. To find south, imagine a line joining the two stars at the head and the foot of the cross. Extend the line out another four lengths from the foot of the cross. Then look straight down to the horizon. You've found south!