Hydrostatic Equilibrium

Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force. For instance, the pressure gradient force prevents gravity from collapsing the Earth's atmosphere into a thin, dense shell, while gravity prevents the pressure gradient force from diffusing the atmosphere into space.

Hydrostatic equilibrium is the current distinguishing criterion between dwarf planets and small Solar System bodies, and has other roles in astrophysics and planetary geology. This qualification typically means that the object is symmetrically rounded into a spheroid or ellipsoid shape, where any irregular surface features are due to a relatively thin solid crust. There are 31 such objects (apart from the Sun), sometimes called planemos, that are currently confirmed to exist in the Solar System, seven more which are virtually certain, and a hundred or so more which are likely.

Read more about Hydrostatic EquilibriumMathematical Consideration

Other articles related to "hydrostatic equilibrium, equilibrium":

Dwarf Planets - Characteristics - Size and Mass
... and the more rounded its shape, until it achieves maximum rounding at hydrostatic equilibrium ... When an object is in hydrostatic equilibrium, a global layer of liquid covering its surface would form a liquid surface of the same shape as the body, apart from small-scale surface features such as ... The extreme example of a non-spherical body in hydrostatic equilibrium is Haumea, which is twice as long along its major axis as it is at the poles ...
Naming Process For Plutoids - Complications Related To "dwarf Planet" Definition
... However, precise regulations as to how hydrostatic equilibrium would be measured were left undefined for the time being ... whatever threshold is ultimately adopted as proof of hydrostatic equilibrium ... named as if it were a plutoid has not achieved hydrostatic equilibrium, the IAU has stated it will be reclassified, but keep its name ...
List Of Dwarf Planet Candidates - Limiting Values
... to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical shape)." Except for Pluto and Ceres, current observations are ... However, Michael Brown estimates that an icy body relaxes into hydrostatic equilibrium at a diameter somewhere between 200 and 400 km ... Vesta appears to have a fully differentiated interior and was therefore in equilibrium at some point in its history, though it apparently is not today ...
Rhea (moon) - Physical Characteristics - Size, Mass and Internal Structure
... yet another paper claimed that the moon may not be in hydrostatic equilibrium meaning that the moment of inertia can not be determined from the gravity data alone ... closest to the moon, he arrived at his old result that Rhea was in hydrostatic equilibrium and had the moment inertia of about 0.4, again implying a homogeneous ... The triaxial shape of Rhea is consistent with a homogeneous body in hydrostatic equilibrium ...

Famous quotes containing the word equilibrium:

    They who feel cannot keep their minds in the equilibrium of a pair of scales: fear and hope have no equiponderant weights.
    Horace Walpole (1717–1797)