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The solar system formation as described by the Nebular Hypothesis starts with a vast cloud of gas and dust, known as a nebula. Over time, gravity pulls this cloud together, causing it to collapse under its own weight. As it collapses, it starts to spin, and this spinning motion causes it to flatten into a disk shape.
The middle of this disk becomes increasingly dense, eventually forming the Sun. Around this central star, small particles begin to stick together, forming clumps that grow into planetesimals. These bodies continue to collide and stick together, eventually creating planets. This process also results in the formation of smaller celestial bodies such as asteroids and comets. The simplicity and coherence of this process have made the Nebular Hypothesis a leading explanation for the formation of our solar system.

Gravity plays a pivotal role in the Nebular Hypothesis and in the overall dynamics of celestial bodies. It is the force that causes the initial collapse of the nebula, leading to the formation of stars and planets.

• Gravity pulls materials together, allowing planetesimals to coalesce into larger planetary bodies.
• It governs the motion of planets and other celestial bodies, keeping them in stable orbits around the Sun.
• It contributes to the eventual shapes and structures of these celestial bodies by pulling materials towards their center, resulting in spherical planets and stars.

Without gravity, the nebula would not be able to contract and form the complex structures of stars and planets that we observe today.

Planetary orbits are a key feature explained by the Nebular Hypothesis. As the nebula spins and collapses, most of its material flattens into a rotating disk. This rotation causes planets to form in roughly the same plane and orbit in the same direction around the Sun.
By examining our solar system, we can see how planetary orbits are:

• Nearly circular, due to the conservation of angular momentum during formation.
• Aligned within a thin plane known as the ecliptic.

This organized structure highlights the influence of the nebular disk from which the planets formed, providing consistent momentum and rotation patterns that persist to this day.

Observations of other star systems have provided strong support for the Nebular Hypothesis. By looking at distant stars in various stages of formation, astronomers can compare their findings to the processes described in the hypothesis.
These observations often reveal:

• Disks of dust and gas surrounding young stars, similar to the early stages of our own solar system.
• The presence of exoplanets that result from the same accretion processes proposed in the Nebular Hypothesis.
• Patterns and compositions that mirror those observed in our solar system.

Through advanced telescopes and technologies, astronomers continue to find more evidence that supports the idea of star and planet formation outlined by the Nebular Hypothesis, showcasing the model’s applicability beyond just our solar system.