Question

According to current scientific theory, how did the planets of the solar system form? Solid grains of various sizes collided and stuck together, building up to make the planets.
Chunks of the early sun split off and began to revolve around what was left. The strong gravitational pull of our sun drew the planets away from other solar systems.
A supernova of another sun threw large, planet-size chunks toward our solar system’s sun.

Answer 1

The first stage of planet formation began when dust grains in the solar nebula formed condensation nuclei around which matter began to accumulate. This first step hastened the critical process of forming the first small clumps of matter. Once these clumps formed, they grew rapidly by sticking to other clumps. They gradually formed larger objects. Dust plays important role in evolution of gas cloud. Dust helps to cool warm matter by radiating heat away in the form of infrared radiation. When cloud cools its molecules move around more slowly, reducing internal pressure and allowing the nebula to collapse more easily. The dust grains speed up the process of collecting enough atoms to form a planet.

Answer 2

D. A supernova of another sun threw large, planet-size chunks toward our solar system's sun.