NationMaster - Encyclopedia: Oblateness

Oblate also refers to a member of the Roman Catholic religious order of the Missionary Oblates of Mary Immaculate, or in some cases to a lay or religious person who has officially associated himself (or herself) with a monastic community such as the Benedictines for reasons of personal enrichment without actually assuming a monastic lifestyle.

An oblate spheroid is an ellipsoid having a shorter axis and two equal longer axes (see the spheroid page for a picture).

Oblateness is a measure for a planet that is a spheroid in shape, bulging outward in the center due to its rotation. Effectively the (fictitious) centrifugal force fights against gravity causing the planet to look more like a sphere stretched at the equator.

Mathematically, oblateness may be defined as

$\epsilon = {R_{e}-R_{p} \over R_{e}} \approx {3 \pi \over 2 G T^{2} \rho}$

where $R e$ the equatorial radius and $R p$ is the polar radius. The approximation is valid in the case of a fluid planet of uniform density; it is a function of the Newtonian constant of gravitation $G$ , the rotation period $T$ and the density $ρ$ .

Categories: Astronomy

Results from FactBites:

Oblate (religion) - Wikipedia, the free encyclopedia (628 words)
	Traditionally, oblates are people, not professed monks, nuns, or friars, who have individually affiliated themselves in prayer with a House of their choice.
	At a later date the word "oblate" was used to describe such lay men or women as were pensioned off by royal and other patrons upon monasteries or benefices, where they lived as in an almshouse or hospital.
	Examples include the Missionary Oblates of Mary Immaculate, the Oblates of St Francis of Rome (founded 1433 in Italy), and the Benedictine Oblates of St Scholastica (founded 1944 in Italy).

Encyclopedia: Oblate (951 words)
	An oblate spheroid is ellipsoid having a shorter axis and two equal longer axes.
	The oblateness, ellipticity, or flattening is a measure for a planet that is a spheroid in shape, bulging outward in the center due to its rotation.
	The flattening, ellipticity, or oblateness of an oblate spheroid is the relative difference between its equatorial radius a and its polar radius b: The flattening of the Earth is 1:298.

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