Definition

Noun: 1. A specific cosmological theory: The planetesimal hypothesis is the theory that the solar system formed through the gradual gravitational accumulation and collision of small, solid celestial bodies called planetesimals.

Usage

The term is used almost exclusively in academic and scientific contexts, specifically in cosmology, astronomy, and planetary science, to describe this historical model of solar system formation. - The planetesimal hypothesis was a significant development in early 20th-century astronomy. - According to the planetesimal hypothesis, planets grew from countless smaller collisions.

Advanced Usage

• The hypothesis is often discussed in contrast with other theoretical models, such as the nebular hypothesis or the capture theory.
  • While the planetesimal hypothesis explained the orbits of the planets, it had difficulties accounting for the Sun's angular momentum.

Variants and Related Words

• Planetesimal (noun): One of the small, solid celestial objects that are the building blocks in the planetesimal hypothesis.
  • The dust and ice in the protoplanetary disk coalesced into planetesimals.
• Planetesimal theory: A synonymous term for the planetesimal hypothesis.

Synonyms

• Planetesimal theory: The most direct synonym.
• Accretion theory: A broader term for the general process of growth by collision and gravity, of which the planetesimal hypothesis is a specific application.

Noun

1. (cosmology) the theory that the solar system was formed by the gravitational accumulation of planetesimals