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 (counterclockwise viewed from above)
Lunar and Planetary Institute image at
http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=175
Some more data to explain:
4. Most planets rotate in this same direction
Mercury 0°
Jupiter 3°
Venus 177°
Saturn 27°
Earth 23°
Mars 25°
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 0.72)
Images: Lunar and Planetary Laboratory:
http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=178
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 at
http://hubblesite.org/newscenter/archive/releases/nebula/emission/2006/41/image/a/
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 at
http://hubblesite.org/newscenter/archive/releases/nebula/emission/2005/35/image/a/
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?
• Rotating, flattening,
contracting disk - solar
nebula!
Equatorial Plane
Orbit Direction
NASA artwork at http://en.wikipedia.org/wiki/Image:Ra4-protoplanetary-disk.jpg
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 at
http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20060724.html
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 at
http://hubblesite.org/newscenter/archive/releases/star/protoplanetary-disk/2005/10/image/a/layout/thumb/
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 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 across
Image: 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
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 at
http://solarsystem.nasa.gov/multimedia/gallery.cfm?Category=Planets&Object=Asteroids&Page=1
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!!
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)
•Lunar samples - 4.5 to 4.6 Ga
•Meteorites - 4.56 Ga
•Earth – 3.9 (or 4.4 Ga)
Lunar meteorite at
http://meteorites.wustl.edu/lunar/stones/mac88105.htm
Meteorite photo by Carl Allen at
http://ares.jsc.nasa.gov/Education/Activities/ExpMetMys/..%5C..%5CSlideSets/ExpMetMys/Slides1-9.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 Return
1/15/2006
• Stardust
Passed through Comet Wild 2 Coma 1/2004
Stardust image at
http://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 at
http://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
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
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 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