Greek Estimates

Front

Eratosthenes' key observation

Back

Angle of the Sun's rays at noon in Alexandria

Front

Eratosthenes' method for Earth's circumference

Back

Measured distance between two cities + angle of Sun's rays

Front

Eratosthenes' assumption about Earth

Back

Perfect sphere

Front

Angle between Earth, Moon, and Sun during lunar phase

Back

Key observation by Aristarchus for Moon distance estimation

Front

Aristarchus's method for estimating Sun's distance

Back

Comparing distance to the Moon with the distance to the Sun

Front

Aristarchus' ratio for Sun and Moon distances

Back

1:400

Front

Method used by Aristarchus to estimate distances to Sun and Moon

Back

Similar triangles

Front

Eratosthenes' method assumption

Back

Sun's rays are Parallel

Front

Eratosthenes distance Alexandria to Syene

Back

800 km

Front

Key aspect in Aristachus' method

Back

Relative size of Sun and Moon in the sky