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In [[cosmogony]], a '''protoplanet''' is a quasi-[[minor planet|planetoid]] which is slightly larger than a [[planetesimal]] and [[orbit]]s within a [[solar nebula]]'s [[protoplanetary disc]]s. |
In [[cosmogony]], a '''protoplanet''' is a quasi-[[minor planet|planetoid]] which is slightly larger than a [[planetesimal]] and [[orbit]]s within a [[solar nebula]]'s [[protoplanetary disc]]s. According to the [[solar nebula|nebular theory]], such objects are formed by the [[accretion (science)|accretion]] of cooled and solidified [[dust]] and ice grains and [[planetesimal]]s made of the same, within the [[protoplanetary disc]] of a [[solar nebula]]. |
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Early protoplanets had more [[radioactive]] elements, the quantity of which has been reduced over time due to [[radioactive decay]]. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being [[planet]]s. In melted zones their heavier [[Chemical element|element]]s sank to the center; while lighter elements rose to the surface; such a process is known as [[planetary differentiation]]. Composition of some [[meteorite]]s show that differentiation took place in some asteroids. |
Early protoplanets had more [[radioactive]] elements, the quantity of which has been reduced over time due to [[radioactive decay]]. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being [[planet]]s. In melted zones their heavier [[Chemical element|element]]s sank to the center; while lighter elements rose to the surface; such a process is known as [[planetary differentiation]]. Composition of some [[meteorite]]s show that differentiation took place in some asteroids. |
Incosmogony, a protoplanet is a quasi-planetoid which is slightly larger than a planetesimal and orbits within a solar nebula's protoplanetary discs. According to the nebular theory, such objects are formed by the accretion of cooled and solidified dust and ice grains and planetesimals made of the same, within the protoplanetary disc of a solar nebula.
Early protoplanets had more radioactive elements, the quantity of which has been reduced over time due to radioactive decay. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being planets. In melted zones their heavier elements sank to the center; while lighter elements rose to the surface; such a process is known as planetary differentiation. Composition of some meteorites show that differentiation took place in some asteroids.
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