Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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 (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 0.7-2) 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 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. How Did We Get a Solar System? Image: LPI 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. 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 protosun 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!! 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 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) •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 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/ 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 at http://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3991 and http://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3984 artist’s impression We Can Also Look Around …. artist’s impression 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 at http://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=4974 and http://www.almaobservatory.org/en/visuals/images/main.php?g2_itemId=3984