Location
Wherever you are on Earth’s surface, in order to describe your location, you need some point of reference. Right now you are probably reading this chapter at your computer. But where is your computer? It may set up in a certain place or you may be on a laptop computer, which means you can change where you are.
In order to describe your location, you could name other items around you to give a more exact position of your computer. Or you could measure the distance and direction that you are from a reference point. For example, you may be sitting in a chair that is one meter to the right of the door. This statement provides more precise information for someone to locate your position within the room.
Similarly, when studying the Earth’s surface, Earth scientists must be able to pinpoint any feature that they observe and be able to tell other scientists where this feature is on the Earth’s surface. Earth scientists have a system to describe the location of any feature. To describe your location to a friend when you are trying to get together, you could do what we did with describing the location of the computer in the room.
You would give her a reference point, a distance from the reference point, and a direction, such as, “I am at the corner of Maple Street and Main Street, about two blocks north of your apartment.” Another way is to locate the feature on a coordinate system, using latitude and longitude. Lines of latitude and longitude form a grid that measures distance from a reference point. You will learn about this type of grid when we discuss maps later in this chapter.
Direction
If you are at a laptop, you can change your location. When an object is moving, it is not enough to describe its location; we also need to know direction. Direction is important for describing moving objects. For example, a wind blows a storm over your school. Where is that storm coming from? Where is it going? The most common way to describe direction in relation to the Earth’s surface is by using a compass.
The compass is a device with a floating needle that is a small magnet. The needle aligns itself with the Earth’s magnetic field, so that the compass needle points to magnetic north. Once you find north, you can then describe any other direction, such as east, south, west, etc., on a compass rose.
North Pole or true north. The geographic North Pole is the top of the imaginary axis upon which the Earth’s rotates, much like the spindle of a spinning top. The magnetic North Pole shifts in location over time. Depending on where you live, you can correct for this difference when you use a map and a compass.
When you study maps later, you will see that certain types of maps have a double compass rose to make the corrections between magnetic north and true north. An example of this type is a nautical chart that sailors and boaters use to chart their positions at sea or offshore.
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