The Formation of Our Solar System

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Lower temp (H, He, CH4, H2O, N2, ice) - outer edges

Planetary Compositions

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How Did We Get a Solar System?

Inner Planets:

Hot – Silicate minerals, metals, no light elements, ice

Begin to stick together with dust  clumps

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How Did We Get a Solar System?

Accretion - particles collide and stick together … or break apart … gravity not involved if small pieces

Form planetesimals, up to a few km across

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How Did We Get a Solar System?

Gravitational accretion: planetesimals attract stuff

Large protoplanets dominate, grow rapidly, clean up area ( takes ~10 to 25 My)

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How Did We Get a Solar System?

Outer Solar System

Cold – ices, gases – 10x more particles than inner

May have formed icy center, then captured lighter gases (Jupiter and Saturn first? Took H and He?)

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How Did We Get a Solar System?

Early burst of solar wind - sweeps debris out of system

Gravitational accretion of gas for protoplanets in the coolest nebular parts

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The Asteroid Belt

? Should have been a planet instead of a debris belt? Jupiter kept it from forming

How Did We Get a Solar System?

Eros image at

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Beyond the Gas Giants - Pluto, Charon and the Kuiper Belt objects

Chunks of ice and rock material

Little time / debris available to make a planet – slower!!

How Did We Get a Solar System?

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Play Doh Activity

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Early in the Life of Planets

Planetesimals swept up debris

Accretion + Impacts = HEAT

Eventually begin to melt materials

Iron, silica melt at different temperatures

Iron sank – density layering

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Planetary Interiors

Differentiation

Separation of homogenous interior into layers of different compositions

Early – hottest time – dense iron-rich material  core

Releases additional heat

Leaves mantle with molten ocean enriched in silica