What is the radius of the Earth

Q- What is the radius of the Earth?

Ans:The radius of the Earth is measured in terms of the distance from the centre of the planet to any point on or near the surface of the earth. When the form of the Earth is shown with the help of an Earth spheroid, this range starts from 3,963 miles or 6,378 kilometres (the equatorial radius) to a minimum of almost 6,357 kilometres (the polar radius). This variation in the radius is since the shape of the Earth is not perfectly spherical.

Occasionally used as a standard of measurement in the scientific disciplines of astronomy and geophysics is the concept of a nominal Earth radius. The International Astronomical Union suggests that the low value be utilised to calculate this specific value.

For the following set of reasoning, a distance of 3,959 miles or 6,371 kilometres with a variation of 0.3 per cent or 10 kilometres is commonly considered the average distance over the whole world. The International Union of Geodesy and Geophysics (IUGG) gives us three values as references. These include, 

The mean radius is also called R1. This is of three radii that are measured at the two equator points and the pole

Next is the authalic radius R2. This radius is for a sphere having the same surface area. 

The last one is known as volumetric radius or R3, and this is the radius of a sphere with volume the same as that of the ellipsoid.

 The mean radius is the average of the three radii measured at the three points. The following are the three values used as references: the average radius, or R1, of three different measurements. The three distances come out to around 6,371 kilometres on average (3,959 miles).