The Earth's only natural satellite is the Moon. It formed over 4 billion years ago, likely when a Mars-sized object collided with Earth. Samples retrieved from the Moon during the Apollo missions are virtually identical to Earth rocks, suggesting the Moon was formed from material ejected from Earth rather than from a separate impacting body. The Moon has no atmosphere or weathering and its surface includes dark basins called maria formed by ancient lava flows, light highlands, and impact craters and rays.

1. The Earth’s MoonThe Earth’s Moon

2. SatellitesSatellites
 Satellite: Any body thatSatellite: Any body that orbitsorbits aa
larger bodylarger body
 1957: First artificial satellite,1957: First artificial satellite,
Sputnik,Sputnik, launched by the Sovietslaunched by the Soviets
 Earth’s onlyEarth’s only naturalnatural satellite is thesatellite is the
moon.moon.

3. The MoonThe Moon
 Force of gravity is 1/6Force of gravity is 1/6thth
that ofthat of
Earth’sEarth’s

4. Lack of atmosphere also means that
there is a huge temperature range:
134o
C in the day, -170o
C at night
Very little gravity so it has no atmosphere;Very little gravity so it has no atmosphere;
therefore it has no weathertherefore it has no weather

5. The MoonThe Moon
 Your weight wouldYour weight would
change, but notchange, but not
your massyour mass

6. The MoonThe Moon
 1969-1972: The US sent 61969-1972: The US sent 6 ApolloApollo
missions to the moonmissions to the moon

7. Moon rotates once every 27.3 days, but appears to take 29.5 days.
It needs time to “catch up” from the delay crated by the rotation of the
earth

8. The Lunar SurfaceThe Lunar Surface
From youngest to oldest -From youngest to oldest -
Rilles : collapsed lava tubesRilles : collapsed lava tubes
Maria: dark areas on the moon;Maria: dark areas on the moon;
made of solidified lavamade of solidified lava
– Remains of ancient volcanoesRemains of ancient volcanoes
– Looks like riverbeds but no water everLooks like riverbeds but no water ever
on moonon moon
Highlands: light areas; created fromHighlands: light areas; created from
meteorites hitting the moonmeteorites hitting the moon

9. Rilles – collapsed lava tubesRilles – collapsed lava tubes
Straight rille
Sinous rille

10. MariaMaria

11. The Lunar SurfaceThe Lunar Surface
 Craters: bowl-shaped depressions,Craters: bowl-shaped depressions,
most from the moons earlymost from the moons early
formation; named for famousformation; named for famous
scientistsscientists
 Rays: streaks that extend from theRays: streaks that extend from the
impact sitesimpact sites
– Most formed 4 billion of years ago from debris
that bombarded all other bodies in solar
system

12. Moon FormationsMoon Formations
 PBS:PBS:
 http://mass.pbslearningmedia.org/resourchttp://mass.pbslearningmedia.org/resourc
e/npls12.sci.ess.eiu.tourmoon/tour-of-the-e/npls12.sci.ess.eiu.tourmoon/tour-of-the-
moon/moon/

13. Rays - streaksRays - streaks

14. Lunar RocksLunar Rocks
 regolithregolith - layer of dust and ground- layer of dust and ground
up rock created from meteoriteup rock created from meteorite
impactsimpacts
 Moons rocks are similar to EarthMoons rocks are similar to Earth
rocks –rocks –
silicatessilicates

15. Galileo Was RightGalileo Was Right
 From the Earth to the Moon: Part 10From the Earth to the Moon: Part 10
– Gathering of lunar rocksGathering of lunar rocks

16. Interior of the MoonInterior of the Moon
 Information found usingInformation found using
seismographsseismographs
 Less dense than the interior of theLess dense than the interior of the
EarthEarth
– Density = mass / volumeDensity = mass / volume

17. Interior of the MoonInterior of the Moon
 Crust is thinner on the Earth-facingCrust is thinner on the Earth-facing
sideside
Mantle pulled closer on Earth-Mantle pulled closer on Earth-
facing side when ancient magmafacing side when ancient magma
below surface existed – makingbelow surface existed – making
crust thinnercrust thinner

19. Interior of the MoonInterior of the Moon
 Core – made of ironCore – made of iron
Determined the iron is solid, unlike Earth’sDetermined the iron is solid, unlike Earth’s
core, because it is not magneticcore, because it is not magnetic
Lack of magnetism is due to lack ofLack of magnetism is due to lack of
convectionconvection

20. Moon’s crustMoon’s crust

21. Current Theory of Moon’sCurrent Theory of Moon’s
CreationCreation
 Giant impact theory: formed whenGiant impact theory: formed when
a Mars-sized object struck thea Mars-sized object struck the
EarthEarth
– Fragments ejected from the EarthFragments ejected from the Earth
(mostly less dense crust and mantle)(mostly less dense crust and mantle)
– Eventually formed moonEventually formed moon
 Explains why the moon is lessExplains why the moon is less
dense than the Earthdense than the Earth

22. Impact TheoryImpact Theory

23. Impact TheoryImpact Theory
 Supported by moon rocksSupported by moon rocks
– Anothrocite – “Genisis Rock”Anothrocite – “Genisis Rock”
– Chemical analysis of the Genesis Rock
indicated it is an anorthosite, composed
mostly of a type of plagioclase feldspar
– formed in the early stages of the solar system,
at least 4 billion years ago.
– recovered in a crater of the Moon, near other
rocks of its kind.

24. Genesis RockGenesis Rock

25. Impact TheoryImpact Theory
 11stst
phase: Mars-sized object struckphase: Mars-sized object struck
the Earththe Earth
 22ndnd
phase: moon was covered withphase: moon was covered with
molten lava – densest materialmolten lava – densest material
moved to the centermoved to the center
 33rdrd
phase: meteorite impactphase: meteorite impact
“punches” through thin crust; liquid“punches” through thin crust; liquid
rock seeps throughrock seeps through
 Current phase: less loose materialCurrent phase: less loose material
in solar system; only rayed cratersin solar system; only rayed craters

26.  http://www.youtube.com/watch?http://www.youtube.com/watch?
v=WGTBJHFNywIv=WGTBJHFNywI

27. Impact TheoryImpact Theory

28. New Theory (2012)New Theory (2012)
 Impact of Mars-sizedImpact of Mars-sized meteoritemeteorite (Theia)(Theia) notnot
likelylikely
 New study of samples of the Moon areNew study of samples of the Moon are
virtually identical with the Earthvirtually identical with the Earth
 Studied titanium isotopesStudied titanium isotopes
 Meteorite sample shown extremelyMeteorite sample shown extremely
diverse titanium isotope compositiondiverse titanium isotope composition

29. New Theory (2012)New Theory (2012)
 Scientists theorize that Theia might haveScientists theorize that Theia might have
been made solely of icebeen made solely of ice
 Or that a proto-Earth was spinning muchOr that a proto-Earth was spinning much
faster, allowing more mixing offaster, allowing more mixing of
compositioncomposition