## What is effective radius of earth?

effective Earth radius: The radius of a hypothetical Earth for which the distance to the radio horizon, assuming rectilinear propagation, is the same as that for the actual Earth with an assumed uniform vertical gradient of atmospheric refractive index.

## How is Earth radius measured?

Since the locations are points on a circle that goes around the earth, the distance between them can be expressed as an arc measurement on a 360-degree circle. For Eratosthenes, the arc was 7.2 degrees. Compute the radius of the earth using the formula C (circumference) = 2 x pi x r (radius).

**What is the radius of Earth?**

6,371 km

Earth/Radius

According to data taken by 183 high-school classes participating in a World Year of Physics project, “Measure the Earth with Shadows”, the radius of Earth is 6563 km, compared to the accepted value for the mean radius of 6371 km. Of course, no one is claiming the size of Earth has actually changed.

**Who determined the radius of the Earth accurately?**

Eratosthenes

More than 2,000 years ago Eratosthenes compared the position of the Sun’s rays in two locations to calculate the spherical size of the Earth with reasonable accuracy. Eratosthenes was born in the Greek colony Cyrene, now the city of Shahhat, Libya. As a young man, he traveled to Athens to pursue his studies.

### Is Earth a perfect sphere?

Even though our planet is a sphere, it is not a perfect sphere. Because of the force caused when Earth rotates, the North and South Poles are slightly flat. Earth’s rotation, wobbly motion and other forces are making the planet change shape very slowly, but it is still round.

### Who calculated radius of Earth?

One such astronomer, Abu Rayhan al-Biruni, also ended up calculating the radius of the earth. Using trigonometry, he calculated the height of a mountain (in present-day Pakistan) by observing the peak from two different points on the plain.

**What is the greatest distance on the surface of the Earth?**

Dankova in Kyrgyzstan to Hindu Tagh in China, is the longest sightline on earth at a whopping 538 km.

**What is the length of one Earth radius?**

Earth radius to Feet ( R ⊕ to ft) conversion calculator of Length measurement, 1 earth radius = 20902230.971129 feet. Toggle Navigation Trust Converter My activities

## What is the authalic radius of the Earth?

Earth’s authalic (“equal area”) radius is the radius of a hypothetical perfect sphere that has the same surface area as the reference ellipsoid. The IUGG denotes the authalic radius as R 2.

## What is the nominal radius of the Earth?

In astronomy, the International Astronomical Union denotes the nominal equatorial Earth radius as, which is defined to be 6,378.1 km (3,963.2 mi). The nominal polar Earth radius is defined as = 6,356.8 km (3,949.9 mi).

**Who was the first person to measure the radius of the Earth?**

Scholars have interpreted Aristotle’s figure to be anywhere from highly accurate to almost double the true value. The first known scientific measurement and calculation of the radius of the Earth was performed by Eratosthenes in about 240 BC.