ocean lecture 3 chapter 1

A galaxy is a huge rotating aggregation of stars, dust,

gas and other debris

are massive spheres of hot glowing gases

Stars convert hydrogen (H) and helium (He) to heavier elements by nuclear fusion as they age

Our Solar System (Sun & planets) was formed of material made in older massive stars which accreted (stuck together and grew larger)

Hydrogen , Helium

98.6%

Water, Methane, Ammonia

1.1%

Silicates, Oxides

.22%

attraction of particles causes planet to grow

causes pressure inside, melting rock and light stuff rises, dense stuff sinks.

Suitable distance from Sun in the Habitable Zone

Condensed from a cloud of gas and dust (molecular cloud or solar nebula) including remnants of older exploded stars (Supernovae)

NEBULAE : Clouds of H , He and DUST

 Gravitational Collapse  Compression

 Heating  Rotation (spin-up)

 Pre-Stellar Spinning Gas + Dust Disk  Core Compression

 Heating to ~4 million O  Ignition of Thermonuclear H to He Fusion

 Stellar Wind Clears Remaining Gases but not Solids  Solid “seeds” clump and PLANETS form  The Sun is in its Main Sequence phase

Molecular cloud of gas + dust etc. collapses (solar nebula)

Spinning disk with hot core (star)

Accretion of particles (seeds) forms planets in disk out from central star

Melting and density separation of planets

Accretion – Growth vs Fragmentation

 Heating – Accretionary and Radioactive Heat

 Melting – Sphericity + Differentiation (density)

 Atmosphere Acquisition  PRIMARY ATMOSPHERES

 H (hydrogen) + He (Helium) from Pre-Solar Nebula

 SECONDARY ATMOSPHERES  Accumulate after Nebula has dispersed  Gas from Comet Ice – H2O, CO2, CO, CH4, NH3, etc.  Erupting Volcanoes – H20, CO2, N2, H2S, SO2, etc.  Heavy Molecules held by Gravity of Planets >0.1 Earth Mas

GAS = Low Density ICE = 1 gm/cc ROCK = 3 gm/cc METAL = 7 gm/cc