Accretion

Accumulation of smaller objects into progressively larger bodies in the solar nebulaThe primitive gas and dust cloud around the Sun from which planetary materials formed. leading to the eventual formation of asteroids, planetesimalsHypothetical solid celestial body that accumulated during the last stages of accretion. These bodies, from ~1-100 km in size, formed in the early solar system by accretion of dust (rock) and ice (if present) in the central plane of the solar nebula. Most planetesimals accreted to planets, but many – and planets. The earliest accretion of the smallest particles was due to Van der Waals and electromagnetic forces. Further accretion continued by relatively low-velocity collisions of smaller bodies in the solar nebulaAn immense interstellar, diffuse cloud of gas and dust from which a central star and surrounding planets and planetesimals condense and accrete. The properties of nebulae vary enormously and depend on their composition as well as the environment in which they are situated. Emission nebula are powered by young, massive until the mass became large enough to develop its own gravityAttractive force between all matter - one of the four fundamental forces. and attract larger material.