SOLAR SYSTEM

Detailed explanation-1: -Planetesimals are formed from the solid component (dust) in the solar nebula (a protoplanetary disk). While orbiting the Sun, planetesimals accrete to form terrestrial (rocky) and Uranian (icy) planets and cores of Jovian (gaseous) planets. This process is called planetary accretion.

Detailed explanation-2: -Protoplanets are built up through the collisions of planetesimals over millions of years. The protoplanets orbit stably around the Sun for a while, but eventually they collide with each other. In about 100 million years, several terrestrial planets, like the ones found in our Solar System, are formed.

Detailed explanation-3: -What is accretion theory? Accretion theory explains the process of small clumps of dust gathering together to gradually form planetesimals. These planetesimals accumulate more materials and form protoplanets. These protoplanets build until they form planets within the solar system.

Detailed explanation-4: -Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other’s orbits and collide, gradually coalescing into the dominant planets.

Detailed explanation-5: -Planetesimals are smaller than protoplanets since many of them collide to form one protoplanet. Some protoplanets are bigger than the moon, while some moons found in planets are considered to be planetesimals.