geoid

Table of Contents

Introduction
Determination of Earth’s figure
- A historical review
  - Spherical era
    - The ancients
    - The introduction of triangulation
  - Ellipsoidal era
- The concept of the geoid
  - Determining the form of the geoid with Stokes’s formula
  - The contribution of orbiting satellites
  - Radar altimetry of the ocean surface
Earth dimensions—radius, mass, and density

References & Edit History Related Topics

Images & Videos

Image shows a sketch of the Earth on graph paper with a photo of the Earth in the background. Blue arrows point to the sketch and the word "FAKE?" appears above in red letters.

How is sea level measured?

Eratosthenes' arc measuring method

reference ellipsoid

variation in Earth's gravitational field

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geoid: Media

geology

Videos

Image shows a sketch of the Earth on graph paper with a photo of the Earth in the background. Blue arrows point to the sketch and the word "FAKE?" appears above in red letters.

Earth is round, but flat-earthers still exist

Can we prove the Earth is round? Well, yes.

Video: Encyclopædia Britannica, Inc.

How is sea level measured?

How is sea level measured?

The people who figure this out are called “geodesists.”

Video: © MinutePhysics (A Britannica Publishing Partner)

Images

geoid

geoid

Deflection of the vertical from the geoid to the spheroid.

Encyclopædia Britannica, Inc.

Eratosthenes' arc measuring method

Eratosthenes' arc measuring method

Eratosthenes' arc measuring method.

Encyclopædia Britannica, Inc.

reference ellipsoid

reference ellipsoid

Elements of a reference ellipsoid.

Encyclopædia Britannica, Inc.

variation in Earth's gravitational field

variation in Earth's gravitational field

The variation in the gravitational field, given in milliGals (mGal), over the Earth's...

Encyclopædia Britannica, Inc.

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