NEBULARHYPOTHESIS OF LAPLACE
NEBULA HYPOTHESIS OF LAPLACE
·
French mathematician
Laplace propounded his ‘nebular hypothesis’ in the year 1796.
·
He explained his
concepts about the origin of the solar system and the earth in his book
entitled ‘Exposition of
the World System’.
·
Laplace’s nebular
hypothesis was almost similar to the gaseous hypothesis of Kant.
·
It appears that
Laplace’s hypothesis is just the modified version of Kant’s hypothesis.
ASSUMPTION
•
He assumed that there was a huge and
hot gaseous nebula in the space.
•
Initially the huge and hot nebula
was rotating on its axis.
•
The nebula was continuously cooling
because of loss of heat from its outer surface through the process of radiation
and
• it was continuously reducing in size due to contraction on cooling.
EXPLAINATION
1.
According to Laplace, Nebula was
continuously reduced in size due to gradual loss of heat from the outer
surface of the nebula through radiation.
2.
Reduction in the size and volume of
the nebula increased the circular velocity of the nebula.
3.
Due to the increase in velocity,
nebula started spinning at very fast speed
4.
The centrifugal force becomes so
great that it exceeded the centripetal force.
5.
The Outer surface was condensed due
to excessive cooling and contracting the central nucleus of the nebula.
6.
Thus the outer ring
was separated from the remaining of the nebula.
7.
This separated ring
started moving around the nebula.
8.
Laplace further
observed that from the original ring, nine rings were thrown off and each ring
moved away from the outer ring.
9.
Thus, nine planets
were formed in our solar system,
10. And the remaining central nucleus
of the nebula becomes the Sun.
Evaluations
q
He did not describe the source of the origin
of the nebula. In similar way kant did not explained.
q
He did not explain that the reason
of thrown off from the cental nebula.
q
If the sun is the remaining nucleus
of the nebula as claimed Laplace, it should have a small bulge around its
middle part which would point out the probable separation of the irregular ring
from the sun but there is no such bulge in the middle part of the sun.
q
According to the nebular hypothesis
all satellites should revolve in the direction of main planets but few
satellites like Saturn and Jupiter revolve in the opposite direction of their
planets.
q
The nebular hypothesis did not
explain the distribution of present-day angular momentum in our solar system.
SAYANTANI SINGH Msc,
B.ED
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