How did Eratosthenes measure the angle of the sun?

Eratosthenes could measure the angle of the Sun’s rays off the vertical by dividing the length of the leg opposite the angle (the length of the shadow) by the leg adjacent to the angle (the height of the pole). This gave him an angle of 7.12 degrees.

How accurate was Eratosthenes measurement?

Values between 500 and about 600 feet have been suggested, putting Eratosthenes’ calculated circumference between about 24,000 miles and about 29,000 miles. While not exactly correct, these assumptions are good enough to make a quite accurate measurement using Eratosthenes’ method.

What did the Eratosthenes do?

Eratosthenes, in full Eratosthenes of Cyrene, (born c. 276 bce, Cyrene, Libya—died c. 194 bce, Alexandria, Egypt), Greek scientific writer, astronomer, and poet, who made the first measurement of the size of Earth for which any details are known.

How did the Greeks measure the distance to the sun?

In the middle of the 2nd century BCE, Greek astronomer Hipparchus pioneered the use of a method known as parallax. With the distance to the Moon known, the stage was set for another Greek astronomer, Aristarchus, to take the first stab at determining the Earth’s distance from the Sun.

What did Eratosthenes do?

How did Eratosthenes measure the angle of elevation of the Sun?

Eratosthenes measured, at his local noon in Alexandria, the angle of elevation of the sun on the summer solstice (21 June). Eratosthenes used the local noon and no other time of the day since at local noon all relevant places and sunrays are placed on the same imaginary plane enabling the use of simple geometry for his calculations.

What time of the day did Eratosthenes use?

Eratosthenes used the local noon and no other time of the day since at local noon all relevant places and sunrays are placed on the same imaginary plane enabling the use of simple geometry for his calculations. In order to repeat Eratosthenes’ experiment you’ll have to do the same.

How did Eratosthenes use geometry to show distance between two cities?

If you want to know how Eratosthenes used Geometry to show that the 1/50 of a circle on the angle measuring device means that the distance between the two cities was 1/50 of the circumference of the earth, I’d be glad to try to explain it. Another question, in 1996, provided the opportunity to go into a little more detail about the geometry:

How big is the Earth according to Eratosthenes?

The exact size of the stadion he used is no longer known (the common Attic stadion was about 185 m), but it is generally believed that Eratosthenes’ value corresponds to between 39,690 km and 46,620 km. The circumference of the Earth around the poles is now measured at around 40,008 km. Eratosthenes result is not bad at all.

https://www.youtube.com/watch?v=O6KOSvYHAmA