#### Readers ask: How Far Off Was Pyolemys Calculation Of The Circumference Of The Earth?

Claudio Posidonius, also known as Ptolemy, lived in Alexandria during the second century CE (Common Era), and his calculations were corrected. He determined the earth’s circumference to be 28,985 kilometers (18,000 miles), which was roughly 28 percent off from Posidonius’ estimate.

Contents

- 1 How did Ptolemy calculate the circumference of the earth?
- 2 How was the circumference of the Earth calculated?
- 3 Is Eratosthenes’s method of determining the circumference of the earth logical and reasonable?
- 4 How an ancient Greek mathematician calculated the Earth’s circumference?
- 5 What is the circumference of the earth according to Eratosthenes calculation?
- 6 Who first calculated the circumference of the earth?
- 7 How many miles is Earth’s circumference?
- 8 What is the calculated circumference of the Earth at the equator?
- 9 How did Eratosthenes estimate the size of Earth in 240 BC?
- 10 How was the size of the Earth first measured?
- 11 Who was the first person to calculate the circumference of the Earth and coined the word geography?

## How did Ptolemy calculate the circumference of the earth?

He discovered that he could estimate the circumference of the Earth by measuring the length of the shadow in Alexandria at noon on the Summer Solstice, while there was no shade in Syene! There are no shadows cast at Syene since the Sun is directly overhead at that moment.

## How was the circumference of the Earth calculated?

You can calculate the circumference of the planet using a geometric formula that has been around for more than 2,000 years! It was discovered by Eratosthenes that the distance between Alexandria and Syene (500 miles) equaled one-fifth of the entire distance around the Earth when he divided 360° by 7.2° and obtained the number 50.

## Is Eratosthenes’s method of determining the circumference of the earth logical and reasonable?

As a result, Eratosthenes reasoned that the ratio of the angular difference in shadows to the number of degrees in a circle (360°) must equal the ratio of the distance between two points on the Earth’s circumference. The final estimate, which is around 25,000 miles (40,234 kilometers) in length, is shockingly precise.

## How an ancient Greek mathematician calculated the Earth’s circumference?

In order to determine the distance between the two cities, Eratosthenes paid a man to pace the distance between them. He discovered that they were 5,000 stadia apart, or around 800 kilometers apart. He could then apply simple proportions to calculate the Earth’s circumference – 7.2 degrees is 1/50 of 360 degrees, therefore 800 times 50 equals 40,000 kilometers, which is the circumference of the Earth.

## What is the circumference of the earth according to Eratosthenes calculation?

Assuming that Strabo’s report of Eratosthenes’ measurement of the circumference of the globe was correct, the circumference would be 24,662 miles and the polar diameter would be 7,850 miles, which is only 50 miles short of the actual polar diameter. This is widely regarded as one of the first great successes of scientific calculation in the history of the world.

## Who first calculated the circumference of the earth?

As the first person to attempt to determine the size of the Earth by measuring its circumference (the distance around the equator) in B.C., the Greek philosopher Aristotle (384-322 B.C.) is credited with doing so. He calculated that the distance was around 400,000 stades (a stadia is a Greek measurement equaling about 600 feet).

## How many miles is Earth’s circumference?

The equatorial circumference of the Earth is about 24,901 miles in length based on these measurements (40,075 km). Earth, on the other hand, is just 24,860 miles (40,008 km) around when measured from pole to pole – the meridional circumference. The form of our planet, which is created by the flattening of the polar regions, is referred to as an oblate spheroid.

## What is the calculated circumference of the Earth at the equator?

The distance around the Earth is known as its circumference. It is 40,075.017 kilometers in circumference around the Equator (24,901.461 mi).

## How did Eratosthenes estimate the size of Earth in 240 BC?

What method did Eratosthenes use to determine the size of the world in the year 240 B.C.? With the use of elementary trigonometry, we were able to determine whether or not sunlight could reach water in water wells in two cities located at opposite latitudes. On the vernal equinox, the earth’s rotational axis and a line connecting the earth and the sun are perpendicular to one another.

## How was the size of the Earth first measured?

While Eratosthenes was in Syene one day when the Sun shined through his wells, Eratosthenes took a reading of the Sun’s position in the sky over Alexandria. Given that it was seven degrees away from the zenith, this implies that Syene is seven degrees distant from Alexandria as measured on the circle that circumscribes the Earth.

## Who was the first person to calculate the circumference of the Earth and coined the word geography?

What is it that Eratosthenes is most well-known for? Eratosthenes calculated the circumference of the Earth geometrically, relying on two surface locations to complete the computation. It was noticed by him that at the summer solstice, the Sun’s rays fell vertically at midday at Syene (now Aswn), Egypt, at noon.