RE: Vanguard and the shape of the Earth - was Articles of generalinterest

Ted Molczan (
Mon, 9 Mar 1998 00:00:25 -0500

Phil Chien wrote:

>It would have been *much* more accurate to describe the Earth as grapefruit
>or orange shaped.  Both are much closer in shape to an oblate spheriod than
>a pear, and more accurate descriptions.
>But I guess we're going to be forever saddled with the description 'pear

The pear shape was not intended to describe Earth's
oblateness, but rather the deviations from oblateness,
as seen in the polar cross-section. The north polar
latitudes are up to 20 metres further from Earth's
centre than the flattened spheroid of 1/298.25. The
mid-northern latitudes are up to 10 m closer to Earth's
centre than the flattened spheroid.

This situation is approximately reversed in the Southern
Hemisphere. So when drawn with these deviations exaggerated,
to make them obvious, the pear shape is a reasonable

Ted Molczan