Formation of Comets

TL;DR

This review discusses the physical evolution of comets from dust grains in the solar nebula to their current state, incorporating empirical evidence from space missions to understand their thermal and collisional history.

Contribution

It provides a comprehensive synthesis of comet formation and evolution, integrating recent empirical data to clarify their primordial nature.

Findings

Comets have undergone significant thermal evolution.

Collisional processes have shaped cometary structures.

Empirical data supports models of comet formation from dust agglomeration.

Abstract

Questions regarding how primordial or pristine the comets of the solar system are have been an ongoing controversy. In this review, we describe comets' physical evolution from dust and ice grains in the solar nebula to the contemporary small bodies in the outer solar system. This includes the phases of dust agglomeration, the formation of planetesimals, their thermal evolution and the outcomes of collisional processes. We use empirical evidence about comets, in particular from the Rosetta Mission to comet 67P/Churyumov--Gerasimenko, to draw conclusions about the possible thermal and collisional evolution of comets.