e mërkurë, 4 korrik 2007

Laplace conceived that the solar system has been evolved from a



gaseous and hot nebula; that the nebulosity extended out
farther than the known planets; and that the entire nebulous
mass was endowed with a slow rotation that was UNIFORM IN
ANGULAR RATE, as in the case of a rotating solid
Laplace conceived that the solar system has been evolved from a
gaseous and hot nebula; that the nebulosity extended out
farther than the known planets; and that the entire nebulous
mass was endowed with a slow rotation that was UNIFORM IN
ANGULAR RATE, as in the case of a rotating solid. This gaseous
mass was in equilibrium under the expanding forces of heat and
rotation and the contracting force of gravitation. Loss of heat
by radiation permitted corresponding contraction in size, and
increased speed of rotation. A time came, according to Laplace,
when the nebula was rotating so rapidly that an outer ring of
nebulosity was in equilibrium under centrifugal and
gravitational forces and refused to be drawn closer in toward
the center. This ring, ROTATING AS A SOLID, maintained its
position, while the inner mass contracted farther. Later
another ring was abandoned in the same manner; and so on, ring
after ring, until only the central nucleus was left. Inasmuch
as the nebulosity in the rings was not uniformly distributed,
each ring broke into pieces, and the pieces of each ring, in
the progress of time, condensed into a gaseous mass. The
several large masses formed from the abandoned rings,
respectively, became the planets and satellites of the solar
system. These gaseous masses rotated faster and faster as their
heat radiated into space, they abandoned rings of gaseous
matter just as the original mass had done, and these secondary
rings condensed to form the satellites; save that, in one case,
the ring of gas nearest to Saturn for some reason formed a
solid (!) ring about that planet, instead of condensing into
one or more satellites. Thus, in outline, according to Laplace,
the solar system was formed.


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