What are Proto-planetary Hypothesis of Kuiper and Hoyle’s Magnetic Theory?

G.P. Kuiper, an American scientist (1951) proposed a modification of Weizsacker’s Hypothesis. He suggested that there existed a flattened and slowly rotating disc-shaped solar nebula bulging out from the equator of the Sun.

This disc-shaped nebula became internally unstable and broke up into smaller concentrations called “proto- planets”, which later on collided and united to form bigger masses which were the planets.

Hoyle’s Magnetic Theory

In 1958 Fred Hoyle propounded his hypothesis, according to which the protoplanetary cloud was created in the process of differentiation of the Sun from an original nebular matter that had been undergoing contraction.

The differentiation of the nebular matter into the Sun and the gaseous cloud was due to fast rotation of the nebular mass. The process of differentiation, however, came to an end due to magnetic coupling between the Sun and the gaseous cloud.

The aggregates of the particles in the gaseous cloud, gave rise to planets.

But this hypothesis did not find much acceptance.