Formation of Our Solar System Modified presentation originally created by the Lunar and Planetary...

Formation of Our Solar System

Modified presentation originally created by the Lunar and Planetary Institute

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

How Did We Get a Solar System?

The cool nebular gas contained about five hydrogen molecules for every helium atom (H - 71%, He - 27% by mass). The temperature in the outer solar system was cold enough for H2 molecules to form.

Image: LPI

How Did We Get a Solar System?

Other elements C, N, O bond with H to form CH4, NH3 and H2O. Astronomers call these “ices” because they can condense into solids in a cold nebula. There may have also been small amounts of CO and CO2. About 0.5% of the nebula was metal and silicate rock.

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 material

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

How Did We Get a Solar System?

Comets

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

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

How Did We Get a Solar System?

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

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

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/

We Can Also Look Around ….

This dusty disc around a newly formed star has a gap, thought to have been carved by newly forming gas giant planets clearing out their orbits as they circle the star.

ALMA images athttp://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3991 andhttp://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3984

artist’s impression

We Can Also Look Around ….

This shows a dust trap in the disc that surrounds the system Oph-IRS 48. The dust trap allows tiny dust particles to clump together and grow to larger sizes. The green area is the dust trap, where the bigger particles accumulate.

ALMA images athttp://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=4974 andhttp://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3984

artist’s impression