Formation of Our Solar System

By the Lunar and Planetary Institute

For Use in Teacher Workshops

Image: Lunar and Planetary Laboratory: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=178

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 athttp://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=175

Some more data to explain:

4. Most planets rotate in this same direction

NASA images edited by LPI

Mercury 0° Venus 177° Earth 23° Mars 25°

Jupiter 3° Saturn 27° Uranus 98° Neptune 30°

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: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=178

How Did We Get a Solar System?

Huge cloud of cold, thinly dispersed interstellar gas and dust – threaded with magnetic fields that resist collapse

Hubble image at http://hubblesite.org/newscenter/archive/releases/nebula/emission/2006/41/image/a/

Image: LPI

Concentrations of dust and gas in the cloud; material starts to collect (gravity > magnetic forces)

How Did We Get a Solar System?

Hubble image at http://hubblesite.org/newscenter/archive/releases/nebula/emission/2005/35/image/a/

Image: LPI

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 http://www.lpi.usra.edu/education/timeline/gallery/slide_1.html

How Did We Get a Solar System?

NASA artwork at http://en.wikipedia.org/wiki/Image:Ra4-protoplanetary-disk.jpg

•Rotating, flattening, contracting disk - solar nebula!

Equatorial Plane

Orbit Direction

•After ~10 million years, material in center of nebula hot enough to fuse H

•“...here comes the sun…”

How Did We Get a Solar System?

NASA/JPL-Caltech Image at http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20060724.html

How Did We Get a Solar System?

Hubble photo at http://hubblesite.org/newscenter/archive/releases/star/protoplanetary-disk/2005/10/image/a/layout/thumb/

•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

How Did We Get a Solar System?

Inner Planets:•Hot – Silicate minerals, metals, no light elements, ice

•Begin to stick together with dust clumpsImage: LPI http://www.lpi.usra.edu/education/timeline/gallery/slide_3.html

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 acrossImage: LPI http://www.lpi.usra.edu/education/timeline/gallery/slide_3.html

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 http://www.lpi.usra.edu/education/timeline/gallery/slide_4.html

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 http://www.lpi.usra.edu/education/timeline/gallery/slide_5.html

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 athttp://solarsystem.nasa.gov/multimedia/gallery.cfm?Category=Planets&Object=Asteroids&Page=1

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

Chunks of ice and rock materialLittle time / debris available to make a planet

– slower!!

How Did We Get a Solar System?

Play Doh Activity

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: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=168

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: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=178

When Did the Solar System Form?

• 4.56 billion years ago

• How do we know? (evidence for formation)

Meteorite photo by Carl Allen athttp://ares.jsc.nasa.gov/Education/Activities/ExpMetMys/..%5C..%5CSlideSets/ExpMetMys/Slides1-9.htm

•Lunar samples - 4.5 to 4.6 Ga•Meteorites - 4.56 Ga•Earth – 3.9 (or 4.4 Ga)

Lunar meteorite athttp://meteorites.wustl.edu/lunar/stones/mac88105.htm

How Do We Know How Our Solar System Formed?

Solar System Samples

Meteorites

Image: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2093 And http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-asteroids.html

• 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 Return1/15/2006

• StardustPassed through Comet Wild 2 Coma 1/2004

Stardust image athttp://stardust.jpl.nasa.gov/news/news97.html

Info and images at http://deepimpact.jpl.nasa.gov/index.cfm

We Can Also Look Around ….

Close-up of "Proplyds" in Orion

Thanks Hubble!

Hubble images athttp://hubblesite.org/newscenter/archive/releases/nebula/emission/1994/24/image/a/ and

http://hubblesite.org/newscenter/archive/releases/nebula/emission/1994/24/image/b/

Comets

• Dirty snowballs - small objects of ice, gas, dust, tiny traces of organic material

Image from: http://antwrp.gsfc.nasa.gov/apod/ap000805.html

Comet Parts

Nucleus, ComaDust tail – white, “smoke,” reflects sun. 600,000 to 6 million miles longIon tail – Solar UV breaks down CO gas, making them glow blue. 10’s of millions of miles

Image from http://hubblesite.org/newscenter/archive/releases/2004/52/image/a/

Image credit: K. Jobse, P. Jenniskens and NASA Ames Research Center http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=903

Naming Comets

NASA/ JPL image of Comet Halley at http://www.solarviews.com/cap/comet/haldet.htm

Where do Comets Originate?

What’s in a Tail?

Image credit: K. Jobse, P. Jenniskens and NASA Ames Research Center http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=903

Comet – Planet Interactions

Image from http://www2.jpl.nasa.gov/sl9/image3.html