# How was the size of the Earth determined?

## How was the size of the Earth determined?

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 did Eratosthenes measure the radius of the Earth?

He found that the arc of the shadow in the hemispherical bowl of the sundial was 1/50 of its circle, and hence concluded that the arc of the earth between Syene and Alexandria, which was 5,000 stadia, was 1/50 of the great circle of the earth.

Who calculated the size of the sun?

Eratosthenes
Eratosthenes also calculated the Sun’s diameter. According to Macrobious, Eratosthenes made the diameter of the Sun to be about 27 times that of the Earth.

### What is the size of the Earth?

6,371 km

What is the actual size of the sun compared to Earth?

The Sun is 864,400 miles (1,391,000 kilometers) across. This is about 109 times the diameter of Earth. The Sun weighs about 333,000 times as much as Earth. It is so large that about 1,300,000 planet Earths can fit inside of it.

Who was the first person to measure the size of the Earth?

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. He had heard that in the nearby town of Syene midday sunlight shines straight down to the bottom of deep wells on…

## How did the ancient Greeks determine the size of the Earth?

The Greeks not only knew Earth was round, but also they were able to measure its size. The first fairly accurate determination of Earth’s diameter was made in about 200 BCE by Eratosthenes (276–194 BCE), a Greek living in Alexandria, Egypt. His method was a geometric one, based on observations of the Sun.

Who was the first Greek astronomer to measure the distance to the Sun?

•Earth orbits the sun: Aristarchus ~250 BC •Size of the earth:Eratosthenes ~200 BC •Precession of earth’s axis: Hipparchus ~130 BC •Moon distance variation: Ptolemy ~150 AD •Evidence for solar distance variation: Ptolemy ~150 AD Same techniques in use today Gaia Satellite

How did ancient astronomers determine the circumference of the Earth?

Here is simple method of establishing circumference (and diameter) of the earth that (most likely) was used by the ancient astronomers.