While you may have heard the words latitude and longitude before, you might not know entirely what they mean; let alone how to read them. With the rise of GPS devices, we simply do not need to know about latitude and longitude like we used to. However, there are still industries and occasions where knowing what the difference is between latitude and longitude is vital.
In the simplest terms, latitude refers to the horizontal lines that can be found on most maps, whereas the vertical lines are called longitude. However, the meaning behind these, how to read them, and the history of them is much more in-depth than that.
What Is Latitude?
Most maps of the world have imaginary lines drawn on them. One that many are familiar with is the equator. While this line does not actually exist on the planet, it perfectly divides the northern and southern halves of Earth on every map. Besides the equator, there are dozens of other lines, which are known as lines of latitude and longitude.
As previously mentioned, lines of latitude run horizontally on a map. They match up with the equator and run parallel to it. These lines are used to determine an object’s position on the Earth in regards to how far north or south it is.
The equator is actually a line of latitude and constitutes to 0° on the map. The further away you move from the equator, the higher that the number will get. It goes all the way up until it reaches the Northern and Southern poles, which are both classified as 90°.
Since the number does not go into the negative, map readers must have some way to distinguish whether their coordinates are North of the equator or South of the equator. They do this by attaching an N for North or an S for South. If a coordinate is 65° and is located South of the equator, then it is referred to as 65° S.
In total, there are 180 lines of latitude on the globe.
What Is Longitude?
Lines of longitude run vertically on a map. These help to determine an object’s location on the Earth in regards to how far East or West it is. Instead of using the equator as its basis for measurements, longitude uses what is referred to as the Prime Meridian.
This line, also known as the Greenwich Meridian, runs from the North Pole to the South Pole and cuts right through the Royal Observatory in Greenwich, England and continues on to pass through the Western tip of Africa.
Further reading: What Is Greenwich Mean Time?
Unlike latitude, which ranges from 0-90°, longitude has a greater measurement range of 0-180°. They are measured as being either East or West of the Prime Meridian, with the exception of 180° which is located on the exact opposite side of the globe from the Prime Meridian. In contrast to latitude, there is a W attached to the end of the coordinate to indicate West or an E to indicate East of the Prime Meridian.
In total, there are 360 lines of longitude around the planet.
What Is the History of Latitude and Longitude?
Latitude and longitude have been used on maps for hundreds of years, but the concepts of both date back much earlier. In fact, humans have been calculating latitude for over 2,000 years. The Greeks calculated latitude by measuring the height of the sun of the horizon at midday. The Polynesians used the stars to help orientate their boats in relation to the Equator.
Eventually, humans began to develop and use sophisticated tools to help them with their latitude calculations. Devices like the gnomon and the Arabian Kamel were used on land, while the quadrant and the astrolabe were being used at sea.
Longitude, on the other hand, took much longer to develop since it is harder to measure, especially at sea. Not knowing where exactly the ships were located could end up having disastrous consequences. Early measurement devices were very unreliable or much too complex. This led to the British Government creating the Longitude Act in 1714, which offered a cash reward to anyone could create a reliable device for measuring longitude at sea.
Many inventors created devices in hopes of claiming the cash prize. However, it wasn’t until around 1761 that a clockmaker named John Harrison finally succeeded. With his spring-driven clock known as the H4, Harrison was able to keep track of longitude within half a degree while at sea. This was groundbreaking and paved the way for even easier devices to be constructed.
The Royal Observatory in Greenwich, England, was the test site for many of these longitude-measuring devices. It became the official spot against which longitude was measured in 1884.
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