Chapter 22 Section 3 Earth’s Moon

Earth vs. Moon 3,475 km 12,756 km Earth has 1 natural satellite  the Moon No specific name other than Moon Unusual because of size in comparison to parent planet (Earth) Density is 3.3 X that of water (= to mantle rocks on E) M core= small E density is 5.5 X that of water Gravity 1/6 th of E 150 lb = 25 lb Moon is ~1/4 th the size of Earth! ~238,000 miles

Earth’s Tides & The Moon

A Trip Inside the Moon

Apollo Missions Most of Moon information gathered from Apollo missions (6 landed on Moon’s surface ). CBS News Coverage Apollo 11

Space Race What was the space race? Who won the space race?

Surface of the Moon Craters: round depressions –Produced by impact of rapidly moving debris –Many craters present due to lack of atmosphere & no tectonic activity –Rays: “splash” marks (dust) radiated from crater on impact (like sun “rays”) Highlands: densely pitted, light-colored areas (mountain-like) –Highest peaks ~8 km (1 km shorter than Mt. Everest) Maria: dark, relatively smooth areas made of basaltic lava (singular mare latin for sea) –Originated from asteroids punctured surface  magma slowly seeped from below surface –Rilles: long channels that were once filled with ancient lava flows (collapsed lava tubes [like a hose with no H 2 O flowing]) Regolith: soil-like layer on surface; gray debris/dust from impact; ~3 m thick

What does the surface of the Moon look like?

Principle of Cross-Cutting Why must have the rays (rayed craters) formed after the maria & rayless craters? They cross-cut them! Older cross is cut by younger; the one cutting is younger than the one being cut Rock A (cutting) is younger than Rock B (being cut)

Moon’s First Birthday Origin of Moon: Impact Theory –During solar system formation –Body about the size of Mars impacted Earth –Liquefied Earth’s surface & ejected crustal & mantle rock This debris entered orbit around Earth & accreted to form Moon Support: 1.Iron-poor mantle & crustal rocks  Moon’s core 2.Zinc isotopes Traces of zinc found on Moon  more heavy/less light in comparison to Earth Moon went through intense evaporation (heat) event early on Intense temperatures allowed lighter zinc isotopes to evaporate leaving behind more of the heavier zinc isotopes

Impact Theory

Timeline of Moon’s Life 1.Formation: formed very “quickly” (few million yrs) 2.Early: formed as liquid and differentiated –Meteor impacted solid crust ~4 billion yrs ago (highlands) 3.Volcanic: lava flows filled basins caused by impacts (~3 billion yrs ago) creating maria 4.Inactive: geoglocially dead for last 3 billion yrs (core solidified)