Difference between revisions of "Equator"
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Revision as of 09:30, 9 April 2007
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Equator
</dt>
The primary
great circle of a sphere or spheroid, such as the earth, perpendicular to
the polar axis;
or a line resembling or approximating such a circle.
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The terrestrial equator is 90� from the earth's geographical poles; the
celestial equator or equinoctial is 90 � from the celestial poles; the
galactic equator or galactic circle is 90� from the galactic poles. The
astronomical equator is a line connecting points having 0� astronomical
latitude; the geodetic equator connects points having 0� geodetic latitude.
The expression terrestrial equator is sometimes applied to the
astronomical equator. The geodetic equator is shown on charts. A fictitious
equator is a reference line serving as the origin for measurement of
fictitious latitude. A transverse or inverse equator is a meridian the plane
of which is perpendicular to the axis of a transverse projection. An oblique
equator is a great circle the plane of which is perpendicular to the axis of
an oblique projection. A grid equator is a line perpendicular to a prime grid
meridian at the origin. The magnetic equator or aclinic line is that line on
the surface of the earth connecting all points at which the magnetic dip is
zero. The geomagnetic equator is the great circle 90� from the geomagnetic
poles of the earth.
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References
This article is based on NASA's Dictionary of Technical Terms for Aerospace Use
