Today – 1/24 Is it spring? Review Radiometric dating Convection Tsunami Mars

Weather Principles Jet stream is a current of fast moving air in the upper atmosphere that drives storms Ridge – northerly arch in the jet stream. Under ridge: high-pressure, warm and dry (usually). Trough – southerly dip in the jet stream. In the trough: low-pressure, wet and cool.

Weather Sites

Titan has Earth-like Processes

Titan has Earth-like Processes No ethane oceans with acetylene icebergs Liquid natural gas (methane) rain and rivers Cryovolcanism – liquid water + ammonia Differentiated: rocky core, water ice mantle. Implies warm phase some time in history Importance: atmosphere like early Earth – nitrogen + soup of organic compounds

Earth

Earth vs. Titan Metallic coreRocky core Rocky mantleIce mantle Rocky crustNo crust Both differentiated, when?

Review Three rock types: igneous, metamorphic, sedimentary Stratigraphy: study of layers of sedimentary rock – superposition, cross-cutting Arizona stratigraphy Radiometric dating

Elements Defined by #Protons

Isotopes An isotope of an element is an atom of the element with a specific number of neutrons: C-14 has 6 protons and 8 neutrons C-13 has 6 protons and 7 neutrons C-12 has 6 protons and 6 neutrons Some isotopes unstable, decay

Atoms Small Lots of them 12 grams of carbon (~1/3 of a piece of charcoal) contains 600,000,000,000,000,000,000,000 atoms,

Uranium Has at least 16 isotopes All isotopes are unstable U-238 → Pb-206, t 1/2 = 4.5 Ga U-238 is called the “parent” atom Pb-206 is called the “daughter” atom U-235 → Pb-207, t 1/2 = 0.7 Ga

Half-life Time needed for the number of parent atoms to be reduced by one-half. i.e. one half of the original material is left unaltered

Age of the Earth Problem: no rocks exist to date Solution: meteorites! Formed fast, ~100 Ma! 4.54 Ga

Formation of the Moon Theories: fission, capture, condensation Problems: low density, no volatiles, oxygen isotopic signature same as Earth Solution: biggest bomb of them all!

Moon formation picture

Moon Oldest rock ~4.4 Ga When did the big bomb hit? Formed in less than a year 14,000 miles away (238,000 now) Made from the same material as the Earth’s mantle – what does this tell us about the timing of core formation?

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