1. Astronomy 3040 Astrobiology Spring_2016 Day-8

2. Project http://www.ulalaunch.com/docs/product_sheet/Delt aIVPayloadPlannersGuide2007.pdf http://www.ulalaunch.com/docs/product_sheet/Delt aIVPayloadPlannersGuide2007.pdf This is the Delta-IV payload guide overview. 20MB. Planetary quarantine program.

3. Course Announcements Colloquium on Friday, Feb. 19. @2:30pm B310 Dr. David James, Cerro-Tololo InterAmerican Obs. Open Clusters, Stellar Evolution and Calibrating the Ages of Stars: Blanco 1 Galactic open clusters are laboratories, provided by nature, for us to study stellar evolution. Using 1m-, 4m- and 8m-class telescopes, I will show how spectroscopic and photometric observations of solar-type stars in open clusters allow us to establish a stellar chronometer, and create an age-ranking system for an ensemble of nearby, well-studied clusters. With the aid of new observations of Blanco 1, an high-Galactic latitude, Pleiades-age cluster, I will show how deriving stellar age must be based upon very high quality observational data and a diverse range of stellar models.

4. Today § 3 HW – 6, 8, 16, 18, 38, 55, 56, 58, 60, 65 Due Monday Feb. 22 1 st quarter observing session 7:30pm tonight

5. Homework Due Wed. Feb. 24 Chapter 4:  3, 9, 18  21, 27, 32  37, 42, 46  49, 50, 54

6. Chapter - 4 Geology & Life  Earth is unique within our solar system Moderate Temperatures (slight greenhouse effect)‏ Abundant water Protective atmosphere Relatively stable environment Contrast Moon, Mercury, Venus, Mars (Fig 4.1)‏  Distance from Sun  Volcanism & Plate Tectonics  Magnetic field

8. Mercur y Mar s Moon Venu s

9. The History of Life on Earth Geological Record – fossils and rock layers  3 basic types of rock (Fig 4.2)‏ Igneous – molten rock that cools and solidifies  Basalt,Granite Metamorphic – transformed under Pressure/Temperature  Marble, Slate Sedimentary – gradual compression of sediments  Important to fossil studies – slow buildup with fossils.  Limestone, Sandstone  Rock Cycle (Fig 4.3) + 4.4, 4.5, 4.6

12. The History of Life on Earth Rock Analysis  3 basic types of rock Mineralogical – identify minerals in the rock Chemical – determine the elemental composition Isotopic – ratio of different isotopes - gives formation age  Radioactive Dating (Fig 4.7)‏ Half-life – probability (Fig 4.8; Table 4.1; Example 4.1)‏  Parent – Daughter isotopes  Compare with geological record  Sometimes, find organic material (Jurassic Park) (Fig. 4.9)‏

13. The Geological Time Scale Al 26 Mg 26 is important for early heating of Earth's core.

15. The History of Life on Earth 4 Eons (Fig 4.10)‏  Hadean - “Hellish”  Archean - “Ancient Life”  Proterozoic - “Earlier Life”  Phanerozoic – Visible Life” Age of the Earth – oldest rocks 4.0 Gyr  “Zircons” (Fig 4.11) ~4.4 Gyr Suggest the crust separated from interior ~4.5 Gyrs  Moon rocks ~4.4 Gyr Therefore, Moon existed by this time.

16. Hadean Earth, Dawn of Life 3 generations of atmospheres  Primary – H, He Planet formation  Secondary – CO 2, H 2 S, SO 2, H 2 O... Outgassing (Fig 4.12), Comet delivery(?)‏  Tertiary – N 2, O 2, H 2 O Modified by life

17. Hadean Earth, Dawn of Life Late Heavy Bombardment – ~3.9 Gyr ago  Relatively quiet between formation and LHB  Since then, protected by Jupiter Sterilizing Impacts  350-400 km in diameter (Fig 4.13)‏ Completely vaporize the oceans Global surface temperature rise 2000 C (3600 F)‏ Last ~4.2-3.8 Gyr ago

19. Impact Energies and these are the small ones

20. Geology & Habitatbility Earth's Interior – Seismic waves (Fig 4.14)‏  Crust – lowest density, Al, Si, Ca  Mantle – rocky “plastic”  Outer Core – molten  Inner Core – solid, Fe, Ni Earth's Interior – Differentiation  Melting and sedimentation of heavy material to core  Al 26 ==> Mg 26 contributed a lot of early heat

22. Geology & Habitatbility Plate Tectonics (Fig 4.15)‏  What is it?  What causes it? Evidence  Continental edge fits (Fig 4.16)‏  Seafloor spreading  Two types of crust Seafloor crust – young, high density basalt, thin Continental crust - old, lower density granite, thick Figs 4.18 - 4.23

24. Magnetic Field Loss of Atmosphere  Thermal escape – light favored over heavy  Impacts  Solar wind stripping Cause  Electrically conducting interior fluid layer  Convection in the fluid layer  Moderate to fast rotation (dynamo effect)‏ Figs 4.24 - 4.25

26. Magnetosphere & Solar Wind Magnetosphere  Protects surface and atmosphere from direct impact  Van Allen Belts Trapped charged particles Directed down to earth at poles