Knowing how to find a place by its coordinates and to find coordinates for a specific place are two key techniques needed to make digital maps.
How do you map something? If you are using pen and paper, you can draw things directly on the paper. However, for digital maps you need to use a grid.
Since the earth is a sphere, we often use latitude and longitude numbers to indicate a point on the earth's surface. These can be thought of a global/planetary “address” that is used by GPS/computers. Longitude lines are always the same length, but latitude lines get smaller closer to the poles. The equator and the prime meridian divide the earth into hemispheres. The equator divides the earth into North and South hemispheres, and the prime meridian divides the earth into East and West hemispheres.
Image sources: R. Vandewalle, https://www.timeanddate.com/geography/longitude-latitude.html
So what can we do with information? We can use the latitude and longitude grid to specify a location in a way that can easily be found on a map. If I tried to find the Illini Union on a map and the map didn't have a record for where this building was, it wouldn't be able to display the correct location. However, if I knew the coordinates of the building and looked there, I would be able to find it!
We use degrees, which can be written like this: º , to refer to a number of latitude or longitude. So for example you can say 40 degrees latitude or 40º latitude.
You also need to specify a direction! +40.109639, -88.227207 is a way of specifying latitude and longitude in a similar fashion to the X and Y axis. The positive + and negative - signs indicate the hemisphere (if there is no + or - sign, that means the number is positive).
Image sources: R. Vandewalle, https://www.excelsupersite.com/easily-convert-decimal-degrees-to-degrees-minutes-seconds-in-excel/
Look at the signs!
Go to https://www.google.com/maps/ and search for "40.109639, -88.227207". It will show the location of the Illini Union! Here the Illini Union is 40 degrees north of the equator and 88 degrees west of the prime meridian. Thus in the northern hemisphere and the western hemisphere. Also note that these coordinates refer to the same place as 40°06'34.7"N 88°13'38.0"W, however the first version is easier for computers to deal with and often used for digital maps.
Above, you could find the Illini Union using the coordinates I provided earlier. Now I'll show you how to find the coordinates of one of your favorite places in Google Maps. Here's how:
the floating menu | the box on the bottom | the sidebar with coordinates |
The coordinates for the Stock Pavilion are roughly "40.101027, -88.227152".
It's important to record them in this order, with a comma and space in between, and don't forget the negative sign before the 88 if you are mapping in Illinois!
Once you can find coordinates for places you want to map, you are ready to move to the next notebook and map things!
Before you start making your map you should think about what you want to map! Find coordinates for important places you want to map. For a large place you may want to get coordinates for the edges.
When you are finished, check out the next notebook: Create Your Own Map.
This notebook was created by R. Vandewalle for the NOBEL project, 2020