Solar nebula

The rotating cloud of gas and dust from which the Sun and Solar System formed, collapsing under gravity into a central star and surrounding disk.

Gravitational collapse: The contraction of matter under its own gravity, often increasing its density and temperature. Gravity drove the nebula’s contraction and concentrated most of its mass at the center.
Interstellar medium: The gas and dust occupying the space between stars in a galaxy. The solar nebula formed from material drawn from this larger galactic reservoir.
Nebular hypothesis: The explanation that stars and planetary systems form through the gravitational collapse of clouds of gas and dust. The solar nebula is the specific historical case underlying this broad formation model.
Calcium-aluminium-rich inclusion: A refractory mineral-rich inclusion in a meteorite, among the oldest dated solids formed in the Solar System. These inclusions preserve early materials produced as the solar nebula cooled.
Angular momentum: A conserved physical quantity describing rotational motion. Conservation of angular momentum helped the collapsing cloud spin faster and flatten.
Molecular cloud: A cold, dense interstellar cloud composed mainly of molecular hydrogen and containing dust. The Sun-forming region was part of a molecular cloud before it collapsed.
Pierre-Simon Laplace: A French mathematician and astronomer who independently developed an early nebular model of Solar System formation. Laplace proposed that a rotating, contracting nebula could produce the Sun and planets.
Chondrule: A small, once-molten silicate sphere found in many primitive meteorites. Chondrules record brief heating events in the young solar nebula.
Accretion: The growth of an object as it gathers matter, often through collisions or gravitational attraction. Dust grains and larger bodies accumulated through accretion in the solar nebula.
Cosmic dust: Small solid particles in space, composed of minerals, carbon compounds, or ice. Dust grains in the nebula provided solid material for planetesimals and rocky planets.

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