planetesimál

A planetesimal is a celestial body believed to have been a crucial building block in the formation of planets. These objects are thought to have been remnants from the early stages of solar system or planetary system formation, specifically from the protoplanetary disk that surrounded a young star. Planetesimals are generally considered to be of kilometer size or larger, distinguishing them from the smaller dust grains and pebbles that would have aggregated to form them.

The prevailing theory of planet formation, known as the core accretion model, suggests that planetesimals were formed through the collision and gravitational attraction of smaller particles in the protoplanetary disk. Over time, these planetesimals would have collided with each other, either accreting to form larger bodies or shattering into smaller pieces. Eventually, some planetesimals grew large enough to become protoplanets, which then continued to accrete material and undergo gravitational interactions to form the planets we observe today. The asteroid belt is thought to contain many planetesimals that did not coalesce into a planet due to the gravitational influence of Jupiter. Understanding planetesimals is key to understanding the processes by which planetary systems form and evolve.