Explanation:

Nebular Hypothesis by Kant-- It explains the formation and evolution of the Solar System (as well as other planetary systems). It suggests that the Solar System is formed from the nebulous material. The widely accepted modern variant of the nebular hypothesis is the solar nebular disk model (SNDM) or solar nebular model. It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. 

Proto planet by Von Wizsacker-- The modern view of the Nebular hypothesis is called the protoplanet hypothesis , and was formed independently by Carl von Weizsacker and Gerard Kuiper. 

Planetesimal theory by Chamberli-- It describes the formation of the solar system. It was proposed as a replacement for the Laplacian version of the nebular hypothesis that had prevailed since the 19th century. The theory was based on the idea that a star passed close enough to the sun early in its life to cause tidal bulges to form on its surface, which along with the internal process that leads to solar prominences, caused material to be ejected repeatedly from the sun. Due to the gravitational effects of the passing star, two spiral-like arms would have extended from the sun, and while most of the material would have fallen back, part of it would remain in orbit. This orbiting material would cool and condense into numerous small bodies that they termed planetesimals and a few larger protoplanets.

Binary Star theory by Russel and Littlelon-- As per this theory there is the existence of many stars as pairs in the universe. Our solar system was born from one of these star pairs which consisted of the sun and another smaller star known as the companion star. A huge-sized third star came into the region of this paired stars and caused tidal explosion in the companion star which was completely disrupted, When the third star came close to the companion star some parts of the companion star, were carried away along with the third star which eventually receded away. The rest fell into the sun's gravitational control, these parts retained by the sun revolved round it and gradually cooled down to form the planets.