Planetesimal Hypothesis Of Chamberlin
system from the original angular momentum of Laplace's nebula shattered the very basis of mono-parental or monistic concepts of the origin of the earth (and the planets). That is why, the idea of biparental or dualistic concept of the origin of the earth started gaining currency and respect among the scientists of the 1st quarter of the 20th century. Planetesimal hypothesis propounded jointly by Chamberlin and Moulton belongs to the dualistic concepts of the origin of the earth.
T.C. Chamberlin, a geologist, in collabora tion with Forest Ray Moulton, an astronomer (both belonged to the University of Chicago, USA) postu lated a new hypothesis popularly known as 'planetesimal hypothesis' for solving the problem of the earth in the year 1905. In fact, the 'planetesimal hypothesis was the revival of earlier 'collision hypothesis' (1749) of the French natural scientist Count de Buffon. Planetesimal hypothesis not only explains the origin of the earth but also throws light on the structure of the earth, the origin of its atmos phere and continents and ocean basins.
Origin of the Earth
Unlike monistic concept (e.g. gaseous hy pothesis of Immanuel Kant and nebular hypothesis of Laplace) the planetesimal hypothesis envisaged the origin of the solar system (and the earth) with the help of two heavenly bodies. According to Chamberlin initially there were two heavenly bodies (stars) in the universe-proto-sun and its companion star. The behaviour and properties of the proto-sun were not like other stars. It was formed of very small particles which were cold and solid. Thus, the proto-sun, unlike Laplace's nebula, was not hot and gaseous rather it was formed of solid particles and was cold and circular in shape. There was another star, termed as 'intruding star' or 'companion star' which was destined to pass very close to the proto-sun. When the intruding star came very close to the proto-sun infinite number of small particles were detached from the outer surface of the proto-sun due to mas sive gravitational pull exerted by the giant intrudingstar. Chamberlin termed these detached small parti cles as planetesimals.
Initially, the detached particles or planetesimals were just like dust particles. The planetesimals were not of uniform size rather a few planetesimals around the proto-sun were of fairly big size. These larger planetesimals became nuclei for the formation of future possible planets. Gradually, large planetesimals started attracting small planetesimals. Thus, numer ous small planetesimals were accreted (added) to the nuclei of large planetesimals and ultimately these large planetesimals grew in the form of planets due to continuous accretion of infinite number of planetsimals. With the passage of time, the remain ing proto-sun changed into the present-day sun. The satellites of the planets were created due to the repetition of the same processes and mecha nisms.
According to the planetesimal theory the main force of the ejection of small jets or planetesimals from the proto-sun was the tidal force exerted by the approaching or intruding star on the outer surface of the proto-sun. "It was not necessary to assume that the earth as a whole was ever in molten condition. It grew from small beginnings by the addition of planetesimal matter, rapidly at first, but with de creasing speed' (S.W. Wooldrige and R.S. Morgan, 1959).
Also Read : Evolution Of Earth full explanation