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How did the solar system form from a cloud of gas and dust?

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Illustration showing the eight planets of the solar system in order from the Sun-Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune-depicted to scale by size, with labeled diameters in miles and kilometers. The Sun is partially visible on the left for comparison. — Solar system The planets (in comparative size) in order of distance from the Sun.

The formation of the solar system is explained by the nebular hypothesis, which posits that the Sun and planets emerged from a rotating cloud of gas and dust known as the solar nebula.12

Gravitational Collapse

The process began when a portion of an interstellar cloud became dense enough to collapse under its own gravity, potentially triggered by random density fluctuations or an external disturbance like a supernova shock wave. As the cloud contracted, it conserved angular momentum by spinning faster and flattening into a rotating disk.32

Formation of the Sun and Planets

As material fell toward the center, potential energy converted into kinetic energy, raising temperatures until thermonuclear reactions ignited the Sun. Within the surrounding disk, dust and gas collided and coalesced into larger bodies called planetesimals.32

Temperature gradients determined the composition of these objects:
* Inner planets: Formed near the Sun where it was too hot for volatiles to condense, resulting in small, rocky bodies.4
* Outer planets: Formed beyond the snow line, where ices could condense, allowing them to grow massive enough to capture abundant hydrogen and helium.4