Planetisimal Hypothesis Explained with Simple Animations

Our solar system's story begins four point six billion years ago, with a vast cloud of gas and dust called the solar nebula.This primordial cloud was composed mainly of hydrogen and helium, with trace amounts of heavier elements.Under the influence of gravity and its own angular momentum, the nebula began to rotate.As gravity pulled the material inward, the cloud began to flatten and spin faster, similar to a figure skater pulling in their arms.The cloud gradually flattened into a rotating disk, with most of the material concentrated in the center.The center of this disk became increasingly hot and dense as material accumulated.Eventually, the central temperature reached about fifteen million degrees Celsius, hot enough for nuclear fusion to begin, marking the birth of our early Sun.Within the rotating disk of the solar nebula, countless microscopic dust particles floated in space.These tiny particles carried electrostatic charges, similar to static electricity.This electrostatic force works just like dust sticking to a TV screen due to static electricity.Over time, these collisions led to progressively larger particles.Starting as microscopic dust, they grew into small clusters.These clusters continued to combine into larger structures.Eventually forming grains and small pebbles.These larger particles continued to float in the solar nebula, like cosmic snowflakes, setting the stage for the next phase of planetary formation.As small bodies in space grew larger through collisions, their gravitational influence became increasingly important.A larger body's gravitational field extends further into space, attracting more nearby objects.These growing bodies, called planetesimals, ranged from just a few kilometers to hundreds of kilometers in size.The gravitational force between objects increases with their mass. As planetesimals grew larger, they became more efficient at attracting nearby material.Like cosmic vacuum cleaners, larger planetesimals cleared their orbital paths of smaller objects, incorporating them into their growing mass.This process continued throughout the early solar system, with planetesimals establishing themselves in distinct orbital paths.As planetesimals grew larger, their increased gravitational pull led to more frequent and violent collisions.The largest bodies began to dominate their orbital paths, either absorbing or ejecting smaller objects.These collisions could have different outcomes depending on the size, speed, and angle of impact.In a successful merger, two bodies would combine to form a larger protoplanet.However, some high-speed collisions were destructive, shattering the bodies into smaller fragments.Over millions of years, the successful mergers led to the formation of protoplanets, which continued to grow by clearing their orbital paths of remaining debris.In the final stage of solar system formation, protoplanets evolved into two distinct types of planets.In the inner solar system, high temperatures and strong solar radiation prevented gases from accumulating. These protoplanets collected mostly rocky and metallic materials.In the outer solar system, where temperatures were much colder, larger protoplanets had strong enough gravity to capture and retain vast amounts of hydrogen and helium from the solar nebula.This process created a clear division in our solar system: smaller, rocky planets close to the Sun, and massive gas giants in the outer regions.And that's how our solar system achieved its final form, with four rocky planets in the inner region and four gas giants in the outer region, all in distinct orbital paths.Thanks for exploring the formation of our solar system with Spark.E!