Q. Who was first to measure the circumference of Earth?
Answer: Eratosthenes
Notes: Eratosthenes, a Greek mathematician and geographer, is credited with being the first person to accurately measure the circumference of the Earth. He did this by comparing the angle of the sun's rays in two different locations and using simple geometry to calculate the circumference of the Earth.

This question is part of 40000+ General Studies MCQ Series Course on GKToday Android app. Question Number: 23 in Introduction to Geography and Geographers in above course in App.