CST Level 1 Land Surveyor Certification Practice

Who calculated the circumference of the Earth in 120 BC?

1. Aristotle

2. Galileo Galilei

3. Eratosthenes

4. Isaac Newton

The correct answer is: Eratosthenes

Eratosthenes is renowned for calculating the circumference of the Earth around 240 BC, making his work significant in the history of geography and mathematics. He achieved this remarkable feat by measuring the angle of the sun's rays at noon in two different locations in Egypt—the city of Syene (now Aswan) and Alexandria. By comparing the shadow cast by a stick in Alexandria with the lack of shadow in Syene, Eratosthenes could determine the angle difference and calculate the Earth's circumference based on the distance between the two locations. This calculation was groundbreaking as it demonstrated a scientific approach to understanding the Earth’s size and showcased the application of geometry in real-world problems. The method he employed relied on the principles of geometry and basic trigonometry, which were innovative for his time. Eratosthenes' precise estimate was remarkably close to modern measurements, showcasing both his intellect and the advanced level of ancient Greek science. The other figures mentioned are significant in their own right but were active in different eras or areas of study. Aristotle was a philosopher whose works included natural sciences but he did not calculate the circumference of the Earth. Galileo Galilei lived in the late 16th and early 17th centuries and made pivotal contributions