First who tried to measure the circumference of the Earth
the first person to attempt to measure the circumference of the Earth
The Greek astronomer Eratosthenes was the first to attempt to measure the circumference of the Earth.
The first to try to measure the circumference of the Earth was the Greek astronomer (Eratosthenes) more than 2,000 years ago, after a period of proving that the Earth was spherical, after the ancient Greek philosopher (Pythagoras) first suggested that the Earth was spherical in 500 BC, but This proposal was rejected because it was considered unreasonable, and decades later the Greek philosopher (Aristotle) proved the validity of the Pythagorean theory and concluded that the Earth is spherical by observing celestial bodies from different locations across the planet, and ancient mathematicians and astronomers tried to prove (Aristotle) wrong, but they In the end, they agreed that the Earth was indeed spherical.
Eratosthenes was the first to attempt to measure the circumference of the globe in the Egyptian city of Alexandria. His full name is Eratosthenes of Cyrene, a Greek polyglot, poet, astronomer, mathematician, librarian, and geographer. It was founded by the Greeks in the Green Mountain in northeastern Libya. Eratosthenes traveled to Athens to complete his studies when he was a young man. Then he returned to Cyrene and made a name for himself in scientific endeavors. Eratosthenes came to Alexandria after the Greek ruler of Egypt sent him to teach his son. When the famous chief librarian of Alexandria died in 236 BC, Eratosthenes was appointed in his place at the age of about forty.
Measuring the circumference of the Earth and studying the Earth
Despite the diversity of Eratosthenes' talents, the study of the Earth was a large proportion of his thinking and knowledge. He was the first to use the word geography. He invented the system of latitude and longitude and drew a map of the world at the time. He drew a catalog of 675 stars, and was the first to attempt to measure the circumference of the Earth based on geometry and trigonometry .
One day (Eratosthenes) heard that the sunlight in the middle of the day in Aswan shines directly until it reaches the bottom of the deep wells on the same day every year, indicating that the sun was directly in this town; But in Alexandria, the sunlight on that date did not reach the bottoms of the wells, but rather fell on their sides. Eratosthenes concluded that the difference in the angle of the incoming sunlight is due to the curvature of the Earth’s surface, and then by measuring this angle, the distance between Alexandria and Aswan was linked to the total dimension of the globe.
On the day when the sun shone on the bottom of the wells at Aswan (the location of Aswan was very close to what we call the Tropic of Cancer, 23.5 degrees north, which is the northernmost latitude in which the sun is directly above it at noon), Eratosthenes measured the position of the sun in the sky above Alexandria , and it was seven degrees from the peak, which means that Aswan must be seven degrees from Alexandria as measured on the circle that represents the circumference of the earth, and since seven degrees is about one 50th of a full circle (360 degrees), it doubled Eratosthenes simply put the distance from Alexandria to Aswan—thought to have been about 515 miles (830 km)—and multiplied it by 50, then roughly calculated the circumference of the Earth as 26,000 miles (42,000 km). This number is only five percent of the accepted modern value of 24. , 860 miles (40,008 kilometers).
Eratosthenes errors when measuring the circumference of the Earth
- Use the ancient Greek unit "stadion" to measure length.
- Assuming that the sun's rays were shining parallel to Alexandria and Aswan.
- Suppose Aswan is at latitude 27°23°.
Eratosthenes correctly developed a formula for calculating the circumference of the Earth. He was the first to attempt to measure the circumference of the Earth, but his estimation included many errors; For example: The ancient Greek unit of length “stadion” was based on the circumference of the average Greek stadium, but sports fields in Greece are 607 feet (approximately 185 meters) while stadiums in Egypt were 517 feet (approximately 185 meters) 157 meters), as Eratosthenes assumed that the sun was shining parallel to Alexandria and Aswan, but the rays in both locations were in fact slightly tilted, so Eratosthenes' calculations were wrong by 16%, while if he used the Egyptian distances, his error would have been less than 2% of the Earth's actual circumference of 24,860 miles (40,008 km), and he miscalculated the longitude and latitude of Aswan.
Attempts to measure the circumference of the Earth
- The scientist's first attempt (Eratosthenes).
- Ptolemy's second attempt.
- The third attempt of the Arabs.
| Ertosthenes measure the circumference of the Earth | 42000 km | Its measurement is more than the actual circumference by 1992 km. |
| Measure the circumference of the globe for Ptolemy | 44400 km | Its measurement exceeds the actual circumference by 4,392 km. |
| Measure the circumference of the globe for the sons of Shaker | 40253 km | Its measurement exceeds the actual circumference by 245 km. |
| Measuring the circumference of the Earth according to Ibn Khaldun | 40435 km | Its measurement exceeds the actual circumference by 427 km. |
| Measuring the circumference of the Earth by Shams Al-Din | 40703 km | Its measurement exceeds the actual circumference by 695 km. |
| Measuring the circumference of the Earth for Al-Maqrizi | 40253 km | Its size exceeds the actual circumference by 245 km |
| Measuring the circumference of the globe for Al-Masudi | 47,355 km | Its size exceeds the actual circumference by 7,347 km |
| Measuring the circumference of the globe for Abu al-Fida | 40253 km | Its measurement exceeds the actual circumference by 245 km. |
| Measure the circumference of the Earth by Al-Biruni | 41200 km | Its measurement exceeds the actual circumference by 1192 km. |
Many geographical sources mention that attempts to measure the circumference of the globe have been made three times throughout history. It was the first attempt of the Greek scientist (Eratosthenes) and what results he reached.
The second attempt of Ptolemy: Ptolemy tried to measure the circumference of the globe, nearly 400 years after the first attempt by Ertosthenes, and in this attempt he relied on latitude circles . 4392 km.
The third attempt of the Arabs: The circumference of the globe was measured at the time of the Caliph al-Ma’mun. Many Arabs tried to measure that circumference, but the measurements differed because of their reliance on non-fixed measurement standards. Such as: a grain of barley, or the arm whose length changed during the time of al-Ma’mun; Among those who tried to measure the circumference of the globe: the sons of Shakir, the scholar Ibn Khaldun, the Damascus historian Shams al-Din (Sheikh al-Rabwa), al-Maqrizi, as well as al-Masoudi, Abu al-Fida, and al-Biruni.
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