Ch. 28 Sec. 2Ch. 28 Sec. 2

The MoonThe Moon

Reaching for the MoonReaching for the Moon

Soviet Union launched Soviet Union launched Sputnik ISputnik I in 1957 in 1957– First step into understanding our spaceFirst step into understanding our space

1961, Soviet astronaut Yuri A. Gagarin 1961, Soviet astronaut Yuri A. Gagarin became first human in spacebecame first human in space

U.S. Project Mercury launched first U.S. Project Mercury launched first American, Alan B. Shepard, in space: 1961 American, Alan B. Shepard, in space: 1961

1969, Apollo Program landed Armstrong 1969, Apollo Program landed Armstrong and Aldrin on the moon: Apollo 11and Aldrin on the moon: Apollo 11

Lunar PropertiesLunar Properties

Our moon, one of the largest known moonsOur moon, one of the largest known moons Only moon for the inner planetsOnly moon for the inner planets Only moon that is solid and rocky, others Only moon that is solid and rocky, others

are iceare ice Moon is 27 % of Earth’s radiusMoon is 27 % of Earth’s radius

Lunar SurfaceLunar Surface

Lunar surface is quite darkLunar surface is quite dark– The The albedoalbedo is only .07% reflective is only .07% reflective– Albedo is the amount of sunlight reflectedAlbedo is the amount of sunlight reflected– B/c of no atmosphere: B/c of no atmosphere:

127 127 ooC in sunlightC in sunlight-173 -173 ooC in darknessC in darkness

Lunar SurfaceLunar Surface

No erosion except that of other impactsNo erosion except that of other impacts HighlandsHighlands

– Light in colorLight in color– Mountainous: heavily covered with cratersMountainous: heavily covered with craters– Impact craters: Ejecta and RaysImpact craters: Ejecta and Rays

Lunar SurfaceLunar Surface

Mare or MariaMare or Maria– Dark smooth plainsDark smooth plains– Rilles: valley like structuresRilles: valley like structures

History of MoonHistory of Moon Moon is aged from 3.8 -4.6 bil. Yrs. OldMoon is aged from 3.8 -4.6 bil. Yrs. Old Moon heavily bombarded in first 800 mil Moon heavily bombarded in first 800 mil

yrsyrs– Resulted in breaking & heating of rocksResulted in breaking & heating of rocks– Formed loose ground layer known as regolithFormed loose ground layer known as regolith

Moon tectonicsMoon tectonics

Infer from seismometer data that moon Infer from seismometer data that moon has layershas layers

B/c of known volcano activity & magnetic B/c of known volcano activity & magnetic field, little to no tectonic act. On moonfield, little to no tectonic act. On moon

Moon formation TheoriesMoon formation Theories Capture TheoryCapture Theory

– Beginning of solar system, an object ventured to Beginning of solar system, an object ventured to close to earth close to earth

– Got caught in the gravity fieldGot caught in the gravity field– Problem: Problem: earth and moon of similar elementsearth and moon of similar elements

If came from somewhere else, would be If came from somewhere else, would be different elementsdifferent elements

Moon formation TheoriesMoon formation Theories

Simultaneous Formation TheorySimultaneous Formation Theory– Earth and moon formed in general area and Earth and moon formed in general area and

the same timethe same time– Moon did not have to be slowed downMoon did not have to be slowed down– ProblemProblem

Different accounts of Iron on moon than Different accounts of Iron on moon than EarthEarth

Moon formation TheoriesMoon formation Theories

Impact TheoryImpact Theory– Gigantic collision on earth that ejected into airGigantic collision on earth that ejected into air– Materials merged together to form the moonMaterials merged together to form the moon– Iron deficient crust and all water would have Iron deficient crust and all water would have

evaporated on collisionevaporated on collision

Impact TheoryImpact Theory