What is Earth's mean radius? - Definition from WhatIs.com


Earth's mean radius

Part of the Mathematics glossary:

The Earth's mean radius is determined as the average distance from the physical center to the surface, based on a large number of samples. The value, symbolized rearth, is equal to approximately 6,371,000 meters (6.371 x 106 m). This is roughly 6,371 kilometers (km) or 3,960 statute miles.

The Earth is slightly oblate, so its radius in the plane of the equator is a little larger than its radius along the rotational axis. In addition, there are irregularities in the surface because of hills, mountains, tides, and rainfall.

Based on the value of rearth given here, the volume of the planet (Vearth), in meters cubed (m3), can be found using the standard formula for the volume V of a sphere in terms of its radius r:

V = (4/3)(pi) r3

where pi represents the ratio of the circumference of a circle to its diameter, an irrational number equal to approximately 3.14159. Based on this formula:

Vearth = 1.083 x 1021 m3

Also see Table of Physical Units and Constants.

This was last updated in September 2005
Posted by: Margaret Rouse

Related Terms


  • irrational number

    - An irrational number is a real number that cannot be reduced to any ratio between an integer p and a natural number q. (WhatIs.com)

  • Fibonacci sequence

    - The Fibonacci sequence is a set of numbers that starts with a one or a zero, followed by a one, and proceeds based on the rule that each number (called a Fibonacci number) is equal to the sum of th... (WhatIs.com)

  • algorithm

    - An algorithm (pronounced AL-go-rith-um) is a procedure or formula for solving a problem. Algorithms are used throughout almost all areas of information technology. (WhatIs.com)


  • Mathematics

    - Terms related to mathematics, including definitions about logic, algorithms and computations and mathematical terms used in computer science and business.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question About Earth's mean radiusPowered by ITKnowledgeExchange.com

Get answers from your peers on your most technical challenges

Tech TalkComment



    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.