Who discoverd the latitiude and longitude?
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When people began to travel long distances over deserts or seas, they needed a way to fix their position. Accordingly, a global grid was developed, incorporating lines of latitude and longitude.
In ancient times, people positioned themselves using landmarks and rudimentary maps. This worked well locally, but different methods were needed for travelling further afield across featureless terrain such as sea or desert. Travellers now required a frame of reference, or co-ordinates, to fix their position.
Latitude
Both the Phoenicians (600 BC) and the Polynesians (400 AD) used the heavens to calculate latitude. Over the centuries, increasingly sophisticated devices, like the gnomon and the Arabian Kamel were designed, to measure the height of the sun and stars above the horizon and thereby measure latitude.
The first instruments used at sea to measure latitude were the quadrant and the astrolabe, both of which had been used for years by astronomers to measure the inclination of stars.
But knowing your latitude wasn’t enough. To determine your exact location you also need to measure your line of longitude.
Longitude
Great minds had tried for centuries to develop a method of determining longitude. Hipparchus, a Greek astronomer (190–120 BC), was the first to specify location using latitude and longitude as co-ordinates. He proposed a zero meridian passing through Rhodes. He further suggested that absolute time be determined by observing lunar eclipses, measuring the time when a lunar eclipse started and finished, and finding the difference between this absolute time and local time. However, his method required an accurate clock, something yet to be invented.
In 1530, Gemma Frisius proposed a new method of calculating longitude using a clock. The clock would be set on departure and kept at absolute time, which could be compared with the local time on arrival. Unfortunately, sufficiently accurate clocks weren’t going to be available for another 230 years or so, but when they were, the method Frisius used was shown to work.
Cracking longitude was not only important for the safety of navigators, but vital for the development of sea-borne trade. In 1567, Philip II of Spain offered a prize to any person who could provide a solution to the problem. This was followed in 1598 by a similar challenge from Philip III, to whom Galileo wrote, telling him that eclipses of Jupiter’s moons would reveal the secret. The King remained unconvinced.
In 1667, the Italian astronomer Cassini was persuaded to visit the Academie Royale des Sciences observatory in Paris. As Galileo had suggested, he used the moons of Jupiter to map the world. The eclipses of Jupiter’s moons were timed in Paris using a pendulum clock. In 1681, Cassini travelled to the island of Goree in the West Indies to repeat his measurements. Absolute time was found on the island by observing the eclipses, and this was compared to local time (obtained using the sun), so enabling the island’s longitude to be calculated.
The problem of determining longitude on land had been solved, but the method was useless at sea because a ship’s movements made it impossible to time the eclipses of Jupiter’s moons accurately.
In ancient times, people positioned themselves using landmarks and rudimentary maps. This worked well locally, but different methods were needed for travelling further afield across featureless terrain such as sea or desert. Travellers now required a frame of reference, or co-ordinates, to fix their position.
Latitude
Both the Phoenicians (600 BC) and the Polynesians (400 AD) used the heavens to calculate latitude. Over the centuries, increasingly sophisticated devices, like the gnomon and the Arabian Kamel were designed, to measure the height of the sun and stars above the horizon and thereby measure latitude.
The first instruments used at sea to measure latitude were the quadrant and the astrolabe, both of which had been used for years by astronomers to measure the inclination of stars.
But knowing your latitude wasn’t enough. To determine your exact location you also need to measure your line of longitude.
Longitude
Great minds had tried for centuries to develop a method of determining longitude. Hipparchus, a Greek astronomer (190–120 BC), was the first to specify location using latitude and longitude as co-ordinates. He proposed a zero meridian passing through Rhodes. He further suggested that absolute time be determined by observing lunar eclipses, measuring the time when a lunar eclipse started and finished, and finding the difference between this absolute time and local time. However, his method required an accurate clock, something yet to be invented.
In 1530, Gemma Frisius proposed a new method of calculating longitude using a clock. The clock would be set on departure and kept at absolute time, which could be compared with the local time on arrival. Unfortunately, sufficiently accurate clocks weren’t going to be available for another 230 years or so, but when they were, the method Frisius used was shown to work.
Cracking longitude was not only important for the safety of navigators, but vital for the development of sea-borne trade. In 1567, Philip II of Spain offered a prize to any person who could provide a solution to the problem. This was followed in 1598 by a similar challenge from Philip III, to whom Galileo wrote, telling him that eclipses of Jupiter’s moons would reveal the secret. The King remained unconvinced.
In 1667, the Italian astronomer Cassini was persuaded to visit the Academie Royale des Sciences observatory in Paris. As Galileo had suggested, he used the moons of Jupiter to map the world. The eclipses of Jupiter’s moons were timed in Paris using a pendulum clock. In 1681, Cassini travelled to the island of Goree in the West Indies to repeat his measurements. Absolute time was found on the island by observing the eclipses, and this was compared to local time (obtained using the sun), so enabling the island’s longitude to be calculated.
The problem of determining longitude on land had been solved, but the method was useless at sea because a ship’s movements made it impossible to time the eclipses of Jupiter’s moons accurately.
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