Oblate Spheroid - flattening factor

The Oblate Spheroid Flattening Factor calculator computes the flattening factor for an oblate spheroid.

INSTRUCTIONS:  Choose units and enter the following:

• b - semi-major axis
• c - semi-minor axis

Oblate Spheroid Flatting factor(f): The factor is returned as a real number.

The Math / Science

The formula for the Oblate Spheroid Flattening Factor is:

         f = (b-c)/b

where:

• f = flattening factor
• b = semi-major axis (Equatorial Radius for the Earth)
• c = semi-minor axis (Polar Radius for the Earth)

The oblate spheroid is an ellipsoid that can be formed by rotating an ellipse about its minor axis.  The rotational axis thus formed will appear to be the oblate spheroid's polar axis. The oblate spheroid is fully described then by its semi-major and semi-minor axes.

One important shape in nature that is close to (though not exactly) an oblate spheroid is the Earth.  The force of gravity alone would pull the matter of the Earth into a sphere.  But the rotation of the Earth causes an outward (centripedal) force along the equator creating a bulge.

Oblate Spheroid Calculators and Data

• Earth WGS-84 Equatorial radius in meters: 6378137.0 m
• Earth WGS-84 Polar radius in meters: 6356752.31424518 m 
• Earth Flattening Factor (WGS-84): 0.00335281066474748071984552861852
• Ellipse flattening factor: F = (Er - Pr)/Er  
• Geocentric to Geodetic Latitude
• Geodetic to Geocentric Latitude
• Slant Range