If you have a piece of paper and a pencil handy, that’s the easiest way to record your shadow observations.
The time when the sun is highest in the sky is referred to as “local noon. " It might not necessarily be 12 noon — it could be any time between 11:30 a. m. and 12:30 p. m. [3] X Research source If you know the time of sunrise and sunset, you can also calculate local noon that way. Add the times of sunrise and sunset, using 24-hour time, then divide by 2. The result will be local noon. For example, suppose the sun rises at 6:30 a. m. and sets at 7:30 p. m. (19:30). Add the two half-hours first to get one hour, then add the hours together to get 26 (19 + 6 + 1). Divide by 2 and you get 13 hours, or 13:00, which would be 1:00 p. m. [4] X Research source
The easiest way to do this is to use an online time zone converter, such as the one at https://www. thetimezoneconverter. com/. Some of these time converters automatically account for whether the area observes daylight savings time, so take that into consideration when entering the time of your local noon.
For example, suppose you’ve determined that local noon at your location is 12:42 p. m. Since your location observes daylight savings time, you would subtract an hour to bring the time to standard time, so your local noon is actually 11:42 a. m. If you use a time converter, you’ll find that when it is 11:42 a. m. in your location, it is 16:42 UTC. You are west of the Prime Meridian and there is a 5-hour difference (300 minutes).
To continue the previous example, you have a 300 minutes’ difference between local time and UTC time. Since 300 divided by 4 is 75, your longitude is 75º west.
If you choose a map that covers too broad of an area, there might not be enough detail for you to figure out where you are. Because of the projection required to render a flat map of the Earth’s surface, large-scale maps, such as atlases, are only accurate to a certain degree. However, they can still be helpful in a pinch.
If you’re not sure of the location you’ve chosen, use the map as a guide. For example, suppose you find a spot that you think is your location. According to the map, if you’re correct, there is a lake approximately 500 feet (150 m) north of you. Travel north until you see the lake.
For example, suppose your location is about halfway between the line for 70º and the line for 80º. You would look at the line for 70º initially as your longitude value. However, since your location is actually past that line, you need to go one step further to get the actual longitude.
To return to the previous example, if your location is about halfway between the line for 70º longitude and the line for 80º longitude, your longitude would be 75º. There are 10 degrees of longitude between the 2 lines on your map, and half of 10 is 5. You would add 5 to the value for the longitude line nearest the Prime Meridian, 70º, to get 75º. Note that you could also get the same answer if you used the further line and subtracted your fractional distance. Just keep in mind the direction the values are increasing. If you have a ruler handy, it can help you make a more precise estimate, especially if it’s difficult to eyeball. Longitude is more precisely measured in minutes and seconds (with 60 seconds in a minute, just like time), or in decimal degrees. Decimal degrees are easier to use with a paper map if you need to get that precise.
Most maps will also indicate whether the longitude is east or west, but it’s good practice to know how to figure this out for yourself. If you’re expressing longitude in decimal degrees, longitude values west of the Prime Meridian are expressed as negative numbers. To return to the previous example, if your location is 75. 5º west of the Prime Meridian, your longitude would be -75. 5º.
For projections, you’ll typically see the name of the person who developed it, the aspects of the projection, or a combination of the two. The Mercator projection is perhaps the most well-known projection, and the most commonly used. The datum is typically 3 capital letters followed by 2 numbers that indicate the year the datum was last updated. For example, the datum used by GPS systems is WGS84, the “World Geodetic System” that was created in 1984. [14] X Research source If you needed to tell anyone your location, you would also need to tell them the datum used so they could use the same datum to enter your coordinates. Otherwise, they could be several hundred miles or kilometers off from your actual location.
While most smartphones are equipped with GPS capability, they might not be as precise as dedicated GPS receivers. They also might not give you the longitude and latitude coordinates for your location.
Most GPS receivers derive coordinates using the WGS84 datum. However, your receiver might be displaying coordinates using a different datum. This can result in “datum shift,” which causes your coordinates to be off. The difference on the ground can translate to several hundred feet or meters off. Usually, it doesn’t matter exactly which datum you’re using. Just make sure the 2 listed are the same.
Longitude might be further specified using minutes and seconds (with 60 seconds in a minute, just as with time measurement) or as a decimal. For example, the longitude of Paris, France is 2º 29’ E, which you would read as “2 degrees, 29 minutes east. “[17] X Research source
