# LATITUDE AND LONGITUDE

## What are latitude and longitude lines?

Lines of latitude and longitude make up a grid system that was developed to help determine the location of points on the Earth. These lines run both north and south and east and west across the planet. Lines of latitude (those that run east and west) begin at the equator, which is zero degrees. They extend to the North Pole and the South Pole, which are 90 degrees north and 90 degrees south, respectively. Lines of longitude (those that run north and south) begin at the Prime Meridian, which is the imaginary line that runs through the Royal Observatory in Greenwich, England. The lines of longitude extend both east and west from the Prime Meridian, which is zero degrees, and converge on the opposite side of the Earth at 180 degrees.

## Which comes first, latitude or longitude?

Latitude is written before longitude. Latitude is written with a number, followed by either "north" or "south" depending on whether it is located north or south of the equator. Longitude is written with a number, followed by either "east" or "west" depending on whether it is located east or west of the Prime Meridian.

## Are lines of longitude and latitude all the same length?

No, they are not. Only the lines of longitude are of equal length. Each line of longitude equals half of the circumference of the Earth because each extends from the North Pole to the South Pole. The lines of latitude are not all equal in length. Since they are each complete circles that remain equidistant from each other, the lines of latitude vary in size from the longest at the equator to the smallest, which are just single points, at the North and South Poles.

## How wide is a degree of longitude?

Though there are only a couple dozen lines of longitude shown on most globes and world maps, the Earth is actually divided into 360 lines of longitude. The distance between each line of longitude is called a degree. Because the lines of longitude are widest at the equator and converge at the Poles, the width of a degree varies from 69 miles (111 kilometers) wide to zero, respectively.

## How wide is a degree of latitude?

Though there are only about a dozen lines of latitude shown on most globes and world maps, the Earth is actually divided into 180 lines of latitude. The distance between each line of latitude is called a degree. Each degree is an equal distance apart, at 69 miles (111 kilometers).

## What do minutes and seconds have to do with longitude and latitude?

Each degree of longitude and latitude is divided into 60 minutes. Each minute is divided into 60 seconds. An absolute location is written using degrees (°), minutes ('), and seconds (") of both longitude and latitude. Thus, the Statue of Liberty is located at 40°41'22" North, 74°2'40" West.

## Why was computing longitude so difficult?

It wasn't until the sixteenth century that clocks were fabricated in such a way that they could accurately tell time both on land and at sea. The only way of determining how far east or west one could go is by plotting the stars in two locations and recording the exact time in both locations simultaneously, and then recording the time and position at the destination. As clocks became more accurate, the ability to measure speed and distance became possible.

## How can I remember which way latitude and longitude run?

You can remember that the lines of latitude run east and west by thinking of lines of latitude as rungs on a ladder ("laddertude"). Lines of longitude are quite "long" because they run from the North Pole to the South Pole.

## How can a gazetteer help me find latitude and longitude?

A gazetteer is an index that lists the latitude and longitude of places within a specific region or across the entire world. Many atlases include a gazetteer, and some are published separately.

Latitude lines run horizontally around the globe, while longitude lines run from north to south.

## How can I find the latitude and longitude of a particular place?

To find latitude and longitude of a particular location, you will need to consult either a gazetteer or a computer database that includes longitude and latitude data. Though gazetteers are readily accessible, they don't include as many places as online databases. There are a number of sites on the Internet that have extensive databases of latitude and longitude and even include such specific places as public buildings.

## Why was the Prime Meridian established at Greenwich?

In 1675, the Royal Observatory in Greenwich, England, was established to study determination of longitude. In 1884, an international conference established the Prime Meridian as the longitudinal line that passes through the Royal Observatory. The United Kingdom and United States had been using Greenwich as the Prime Meridian for several decades before the conference.