In the mid-20th century, satellites helped measure Earth's circumference, but over 2,000 years ago, a Greek mathematician named Eratosthenes estimated it using a simple stick experiment. By observing shadows in Alexandria and Syene, he deduced Earth's curvature and calculated its circumference with remarkable accuracy. This video explores his method and its historical significance.

What technological advancement in the mid-20th century helped us measure Earth's circumference?

• The invention of the telescope

• The development of GPS

• The launch of satellites

• The creation of the internet

Who was the Greek mathematician that calculated Earth's circumference over 2,000 years ago?

• Pythagoras

• Aristotle

• Eratosthenes

• Archimedes

What observation did Eratosthenes make in Syene that was crucial to his calculation?

• The sun was directly overhead at noon

• The stars were visible during the day

• The moon was visible at noon

• The sun cast a long shadow at noon

What did Eratosthenes conclude from the difference in shadow angles between Alexandria and Syene?

• The Earth's surface is curved

• The Earth is a cube

• The Earth is a pyramid

• The Earth is flat

Which ancient philosopher first proposed the idea of a spherical Earth?

• Plato

• Socrates

• Homer

• Pythagoras

How far apart did Eratosthenes find Alexandria and Syene to be?

• 10,000 stadia

• 1,000 stadia

• 2,500 stadia

• 5,000 stadia

What mathematical method did Eratosthenes use to calculate Earth's circumference?

• Algebraic equations

• Trigonometry

• Simple proportions

• Calculus

What was the approximate circumference of the Earth calculated by Eratosthenes?

• 30,000 km

• 20,000 km

• 50,000 km

• 40,000 km

What tool did Eratosthenes use to measure the shadow angle?

• A compass

• A sundial

• A stick

• A protractor

What was the significance of Eratosthenes' calculation?

• It proved the Earth was flat

• It demonstrated the Earth was hollow

• It was the first accurate measurement of Earth's circumference

• It showed the Earth was the center of the universe