# 3 ways to determine latitude and longitude

## Table of contents:

Latitude and longitude can be used to determine the exact location of any point in the world. There are several ways to find your latitude and longitude, some of which require far more resources than others. Find your coordinates with a map and protractor once you understand latitude and longitude.

## Steps

### Method 1 of 3: Understand Latitude and Longitude

#### Step 1. Understand latitude

Latitude measures how north or south a point is from the equator. Because the Earth is round, the distance from the equator is measured in angular degrees, with the equator being 0 degrees and the northernmost point (the North Pole) being 90 degrees. The southernmost point (the South Pole) is also at 90 degrees.

### Latitude is measured in degrees of northern latitude when the point is in the northern hemisphere and in degrees of southern latitude when it is in the southern hemisphere

#### Step 2. Understand the length

Longitude measures how east or west a point is on the prime meridian (arbitrarily set at Greenwich, England). Because the Earth is round, the distance from the prime meridian is measured in angular degrees, the prime meridian being at 0 degrees longitude. When moving east or west, the longitude measures up to 180 degrees from the prime meridian.

• The 180 degrees of longitude is known as the international date change line.
• Longitude is given in degrees of eastern longitude when the point is in the eastern hemisphere and in degrees of western longitude when it is in the western hemisphere.

#### Step 3. Know the accuracy of your readings

Degrees are a large unit of measurement, so to get an accurate location, latitude and longitude are divided up to the decimal point referred to as decimal degrees. For example, you can view the latitude as 35.789 degrees north latitude. GPS often show decimal degrees but printed maps do not.

### Online topographic maps express the decimal degrees of longitude and latitude in degrees, minutes, and seconds. Each degree is equal to 60 minutes, while each minute is equal to 60 seconds. Comparison with time allows for easier subdivision

#### Step 4. Understand how coordinates appear on a map

First, always assume that the top of the map is north. The numbers on the right and left of the map refer to latitude. The numbers at the top and bottom of the map are the longitude.

• Remember how to convert time to understand a map that uses decimal degrees as degrees, minutes, and seconds:

• 15 seconds = a quarter of a minute = 0.25 minutes
• 30 seconds = half a minute = 0.5 minutes
• 45 seconds = three-quarters of a minute = 0.75 minutes

### Method 2 of 3: Use a Map

#### Step 1. Get a map from the US Geological Survey (USGS)

A U. S. Geological Survey map is a standardized map created by the National Cooperative Geological Mapping Program under the U. S. Department of the Interior. You can find these types of maps at your local library or obtain them from surveyors or surveyors. other commercial sellers.

#### Step 2. Find the latitude and longitude

These measurements are often in the corner of the map. Below the title you can also know how much the map covers. For example, a map might say that it is a 7.5 minute map, which means that the area it shows is 7.5 minutes of latitude and longitude.

#### Step 3. Find the location

Depending on the scale of your map, it may take a while to find the location. Make a note of the city, town, or specific point on the map that denotes your current position. Once you find it, mark your location. The map legend will tell you the scale so that you can quickly estimate the relative distance to known landmarks if you don't know the name of your city. This can help you find your location more quickly.

### Depending on what you are trying to locate, be sure to use a map with an appropriate scale. If you want to find how far a state is from yours, you should use a map of your country instead of one of the world

#### Step 4. Use a map ruler to check the grades

Measure outward from your location to the straightest numbered line of latitude or longitude. The map will be divided into both vertical and horizontal lines to represent longitude and latitude measurements. The four corners of the map will show both latitude and longitude coordinates in full. Only the last two digits will be displayed for all other waypoints.

• On your map, the latitude and longitude lines should form a grid and divide the map into cross sections. A map ruler is easy to use and can be purchased at an outdoor supply store or online. Make sure the ruler matches the USGS 1: 24,000 scale series of maps.
• Measure latitude first. The latitude lines will be parallel to the north and south of your location. Place the end of the ruler where 0 is in parallel to the south. The end of the ruler that reads 2.5 minutes should be at the next parallel to the north. One edge of the ruler will be marked in minutes and seconds while the other will be in decimal degrees. Make sure to use the correct border that corresponds to the coordinate format of your map. Slide the ruler to the right (or west) until it touches your location. Mark how much distance there is between your location and the parallel to the south. Add it to the latitude of parallel to the south to get the latitude of your location.
• To measure longitude, you should place the ruler diagonally on the west and east meridians with the end of the ruler marking 2.5 minutes touching both meridians. The lines of longitude on your map will be the meridians east and west of your location. You must measure diagonally because if you measure horizontally, the ruler will extend beyond the grid because the meridians of longitude get closer as they move away from the equator. Move the ruler vertically until you find your location, making sure to keep both ends of the ruler on the meridians diagonally. Record where your location is (in minutes and seconds) west of the eastern meridian. To find the longitude of your location, add your measurement to the longitude of the eastern meridian.

#### Step 5. Write down your coordinates

The standard procedure is to write the latitude first followed by the longitude, both written to as many decimal places as possible. The more decimal places you can achieve, the more precise and accurate the location will be.

• By writing down your coordinates, you can give the latitude and longitude three different formats:

• degrees (g.g °): 49.5000 °, -123.5000 °
• minutes (g ° m.m '): 49 ° 30.0', -123 ° 30.0 '
• seconds (g ° m's): 49 ° 30'00 "N, 123 ° 30'00" W
• When dealing with latitude and longitude, the north-south and east-west indicators are removed and replaced with negative values for points south of the equator.

### Method 3 of 3: Measure Using a Protractor

#### Step 1. Make sure it's noon

Determining the latitude with the sun can only be done when the sun is at its highest point. Check your watch or use the method of creating a dial and placing a stick on the ground at the southernmost end of a north-south line. It will be noon as soon as the shadow of the stick crosses the line from north to south.

### Use a plumb bob to ensure that the pole is vertical. A plumb bob is exactly what it sounds like: a line with any kind of plumb attached to it. Gravity will ensure that the poise creates a vertical line

#### Step 2. Use a compass to set north and south

You can only set your measurements knowing the north and south. Mark north and south with a line that runs along the ground. Establish a quadrant with its framing beam parallel to this line.

#### Step 3. Create a quadrant, or cross, using two pieces of wood

The framing beam (or the arms of the cross) must be centered on the support beam (or the body of the cross) so that it can pivot up and down. There should be 4 nails in the arms of the cross, each one only driven in enough to keep it stable. There should be 2 nails at each end of the front of the cross and 2 nails at each end of the upper arms of the cross.

### Center a protractor at the pivot point. Also suspend the plumb bob from this pivot point

#### Step 4. Align the observation nails on the dial with the sun

Once it's noon, line up the nails on the framing beam with the sun. Do not look directly at the sun but use the shadows of the nails to find the correct position. Move the framing beam up and down so that the two nail shadows come together and create a single shadow on the ground.

#### Step 5. Use the protractor to measure the small angle between the beam and the plumb line

Once the beam is pointed correctly, use the protractor to measure from the vertical plumb bob to the closest part of the framing beam. Keep the horizon at 90 degrees when taking measurements.

#### Step 6. Understand that the time of year influences the accuracy of your reading

The reading will only be correct on both the spring and fall equinoxes that occur in March and September, respectively (or vice versa, if you live in the southern hemisphere). If you are taking measurements around December 21, or in the dead of winter (or summer, in the southern hemisphere), subtract 23.45 degrees from your reading. In contrast, add 23.45 degrees if you are taking measurements around the middle of summer (or winter, in the southern hemisphere), on June 21.

• Measurements are not completely accurate outside of the spring and autumn equinox due to the way the Earth is tilted as it orbits the sun.
• While there are complex tables that give you the correct factor to determine your exact latitude and longitude at any given time, estimate accurately based on the date relative to the spring and fall equinoxes. For example, if you are measuring in early May or November, which are midway between the vernal equinox (when the sun is directly over the equator) and summer (when the sun is over 23.45 degrees north of the equator), you would simply add half the 23.45 degrees (11.73) to your measurement.

## Advice

• Online calculators can also be used as a simple method to calculate latitude and longitude.
• You can download applications for mobile devices to help determine longitude and latitude, including GPS applications.