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## How did Aristotle measure the circumference of the earth?

By measuring the length of the shadow in Alexandria at noon on the Summer Solstice when there was no shadow in Syene, he could measure the circumference of the Earth! At Syene: The Sun is directly overhead, no shadows are cast at that moment.

**How did the Earth get measured?**

Earth’s circumference was first accurately measured more than 2,000 years ago by the Greek astronomer Eratosthenes, who at the time lived in the Egyptian city of Alexandria. On the day the Sun shone on the bottom of the wells in Syene, Eratosthenes measured the Sun’s position in the sky over Alexandria.

**What did Eratosthenes believe in?**

To calculate the circumference of the Earth, Eratosthenes measured the angle of the shadow to the Earth. Until he realized this, Eratosthenes believed that the sun was so far away that its rays were parallel.

### How did ancient Egyptians measure the earth?

In the third century BCE , Eratosthenes, a Greek librarian in Alexandria , Egypt , determined the earth’s circumference to be 40,250 to 45,900 kilometers (25,000 to 28,500 miles) by comparing the Sun’s relative position at two different locations on the earth’s surface.

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

Eratosthenes measured Earth’s circumference mathematically using two surface points to make the calculation. He noted that the Sun’s rays fell vertically at noon in Syene (now Aswān), Egypt, at the summer solstice.

**How was the diameter of the Earth calculated?**

This means that Eratosthenes estimated the circumference of the Earth to be about 40,000 km. He also knew that the circumference of a circle was equal to 2 times π (3.1415…) times the radius of the circle. The diameter of a circle is twice the radius, giving us a diameter for Earth of 12,756 km.

## What is the formula of Earth?

The formula for calculating the circumference of a sphere is 2 x pi x radius. So, the radius of the Earth is 6371 km. Plug that into the formula, and you get 2 x 3.1415 x 6378.1 = 40,074. It would be more accurate if you use more digits for pi.

**Who calculated size of Earth?**

Eratosthenes of Cyrene

The first person to determine the size of Earth was Eratosthenes of Cyrene, who produced a surprisingly good measurement using a simple scheme that combined geometrical calculations with physical observations. Eratosthenes was born around 276 B.C., which is now Shahhat, Libya. He studied in Athens at the Lyceum.

**Who discovered the Earth?**

Eratosthenes

By around 500 B.C., most ancient Greeks believed that Earth was round, not flat. But they had no idea how big the planet is until about 240 B.C., when Eratosthenes devised a clever method of estimating its circumference.

### What is Eratosthenes full name?

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.

**What is Earth’s approximate size?**

about 24,901 miles

Using those measurements, the equatorial circumference of Earth is about 24,901 miles (40,075 km). However, from pole to pole — the meridional circumference — Earth is only 24,860 miles (40,008 km) around. Our planet’s shape, caused by the flattening at the poles, is called an oblate spheroid.

**What is the size of Earth?**

6,371 km

Earth/Radius

## Who was the first person to measure the circumference of the Earth?

Eratosthenes’ Calculation of Earth’s Circumference. In 240 B.C., the Greek astronomer Eratosthenes made the first good measurement of the size of Earth.

**Who was the first person to accurately measure the?**

Who Was The First Person To Accurately Measure The Circumference Of The Earth? 1 Measuring the Earth. Eratosthenes is considered the inventor geography, particularly because he developed the system of latitudinal and longitudinal lines to map the world. 2 Method. 3 Errors and Estimates.

**How did Eratosthenes calculate the size of the Earth?**

Because seven degrees is about one 50th of a full circle (360 degrees), Eratosthenes simply multiplied the distance from Alexandria to Syene — believed to have been about 515 miles (830 km) — by 50. He calculated Earth’s circumference at 26,000 miles (42,000 km), only five percent away from the modern accepted value of 24,901 miles (40,074 km).

### Which is the oldest measurement of the size of the Earth?

> Eratosthenes (the oldest measurement of the size of Earth for which details survive) was made in the 3rd century bce. Eratosthenes used the fact that at noon on the summer solstice, the Sun was directly overhead in Syene (a town on the upper Nile, at…