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Formation of Our Solar System. By the Lunar and Planetary Institute For Use in Teacher Workshops. Image: Lunar and Planetary Laboratory. Some data to explain: 1. Planets isolated 2. Orbits ~circular / in ~same plane
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Formation of Our Solar System By the Lunar and Planetary InstituteFor Use in Teacher Workshops Image: Lunar and Planetary Laboratory
Some data to explain: 1. Planets isolated 2. Orbits ~circular / in ~same plane 3. Planets (and moons) travel along orbits in same direction…. same direction as Sun rotates (counter-clockwise viewed from above) Lunar and Planetary Institute image
Some more data to explain: 4. Most planets rotate in this same direction Mercury 0° Venus 177° Earth 23° Mars 25° Jupiter 3° Saturn 27° Uranus 98° Neptune 30° NASA images edited by LPI
And some more data to explain: 5. Solar System highly differentiated: Terrestrial Planets (rocky, dense with density ~4-5 g/cm3) Jovian Planets (light, gassy, H, He, density 0.7-2) Images: Lunar and Planetary Laboratory
How Did We Get a Solar System? Image: LPI Huge cloud of cold, thinly dispersed interstellar gas and dust – threaded with magnetic fields that resist collapse Hubble image
How Did We Get a Solar System? Image: LPI Concentrations of dust and gas in the cloud; material starts to collect (gravity > magnetic forces) Hubble image
How Did We Get a Solar System? Gravity concentrates most stuff near center Heat and pressure increase Collapses – central proto-sun rotates faster (probably got initial rotation from the cloud) Image: LPI
How Did We Get a Solar System? • Rotating, flattening, contracting disk - solar nebula! Equatorial Plane Orbit Direction NASA artwork
How Did We Get a Solar System? • After ~10 million years, material in center of nebula hot enough to fuse H • “...here comes the sun…” NASA/JPL-Caltech Image
How Did We Get a Solar System? • Metallic elements (Mg, Si, Fe) condense into solids at high temps. Combined with O to make tiny grains • Lower temp (H, He, CH4, H2O, N2, ice) - outer edges Planetary Compositions Hubble photo
How Did We Get a Solar System? Inner Planets: • Hot – Silicate minerals, metals, no light elements, ice • Begin to stick together with dust clumps Image: LPI
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 Image: LPI
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) Image: LPI
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?) Image: LPI
How Did We Get a Solar System? The Asteroid Belt ? Should have been a planet instead of a debris belt? Jupiter kept it from forming Eros image
How Did We Get a Solar System? 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!!
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 Image from LPI
Pause to recall the Play Doh accretion activity But wait, there’s more …. We can differentiate!
When did Our Solar System Form … How do We Know? Image: Lunar and Planetary Laboratory
When Did the Solar System Form? • 4.56 billion years ago • How do we know? (evidence for formation) • Lunar samples - 4.5 to 4.6 Ga • Meteorites - 4.56 Ga • Earth – 3.9 (or 4.4 Ga) Lunar meteorite Meteorite photo by Carl Allen
Earliest history of Solar System - chemical and physical info about formation and building blocks of planets (rest of stuff was pulled into the Sun or other planets….) Sample Return 1/15/2006 • Stardust Passed through Comet Wild 2 Coma 1/2004 Stardust image
We Can Also Look Around …. Close-up of "Proplyds" in Orion Thanks Hubble! Hubble images
Comets • Dirty snowballs - small objects of ice, gas, dust, tiny traces of organic material
Comet Parts Image credit: K. Jobse, P. Jenniskens and NASA Ames Research Center Nucleus, Coma Dust tail – white, “smoke,” reflects sun. 600,000 to 6 million miles long Ion tail – Solar UV breaks down CO gas, making them glow blue. 10’s of millions of miles
Naming Comets NASA/ JPL image of Comet Halley
What’s in a Tail? Image credit: K. Jobse, P. Jenniskens and NASA Ames Research Center