What role does gravity play in planetary formation?

Gravity plays a crucial role in planetary formation by pulling together dust and gas to form larger bodies.

In the early stages of a solar system, a nebula - a vast cloud of gas and dust - exists in space. Gravity, one of the fundamental forces of nature, begins to act on this nebula. The particles within the nebula are attracted to each other due to gravity, causing them to clump together and form larger bodies. This process is known as accretion.

As these bodies grow in size, their gravitational pull also increases. This allows them to attract even more particles, leading to further growth. Over time, these bodies can become large enough to form planetesimals, the building blocks of planets. The process of planetesimal formation is largely driven by gravity. Without gravity, the particles within the nebula would remain dispersed and would not come together to form larger bodies.

Gravity also plays a role in shaping the planets. As a planetesimal grows in size, its gravity can cause it to become spherical. This is because gravity pulls equally from all directions, causing the material to distribute itself evenly and form a sphere. This is why most planets, including Earth, are spherical in shape.

Furthermore, gravity is responsible for the formation of planetary systems. The gravity of the central star (like our Sun) keeps the planets in their orbits. Without gravity, the planets would not be held in their orbits and would simply drift away into space.

In conclusion, gravity is a fundamental force in planetary formation. It drives the process of accretion, shapes the planets, and holds the planetary system together. Without gravity, the universe as we know it would not exist.