
Albedo: amt of sunlight reflected off a surface
 Moon’s low albedo=7%
 Earth’s albedo is higher=31%
Impact craters: objects that hit moon’s surface
Highlands: light in color, mountainous
Maria: dark, smooth, lava filled features
Ejecta: stuff evacuated from impact, falls to
surface
 Rays: long trails of ejecta
 Rilles: collapsed lava tubes [like a hose with no
H2O flowing]
 Regolith: loose, ground-up moon rock
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• Principle of Cross-cutting
relationships
-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)
•Cross-Cutting w/s
Seismometers measure annual moonquakes
Moon not tectonically active, no erosion
Crust thinner on Earth side
Solid upper mantle
Partially melted lower mantle
Solid iron core
Impact theory: supported by
similarities btw E and M rocks
(Made of silicates), age of rocks
3.8-4.6 billion years
-Theories of Moon’s formation w/s
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Impact Theory
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Elliptical orbit: planets &
moon revolve on a slightly
squished circle
Ecliptic plane: path planets
travel around Sun
Apogee=furthest (away)
Perigee=closest
Earth:
 24 hr rotation
 365 day revolution
 tilt on axis 23.5°
 Day/night =rotation of
Earth on own axis
 FOLLOW SOLAR DAY
FOR TIMEKEEPING

The day is measured using the Sun.
 Local Solar Noon
▪ Occurs when the Sun is on your meridian.
 Mean Solar Day
▪ The time between successive ‘Noons’.

When noon occurs depends on
your longitude:
 Person 15° east of you sees noon 1 hour earlier.
 Person 15° west of you sees noon 1 hour later.
The year is also divided into 12 months. Why 12?
 There are 12.4 lunar synodic periods (cycles of phases)
during a year.
 The word for Month derives from the word for the Moon.
 Months are divided into Weeks:
 The week is traditionally divided into
7 days; Seven for the 7 planets/moving
bodies visible to the naked eye
(Sun, Moon, Mercury, Venus, Mars,
Jupiter, and Saturn)

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Spring & Fall Equinox:
 Equal radiation in both
hemispheres
 Axis perp. to rays
 Sun directly over
equator

Winter Solstice:
 N hemi tilted away Sun
 less direct radiation

Summer Solstice:
 N hemi tilted to Sun
 more direct radiation

Waxing: light
increasing
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Waning(whiningbad):
light decreasing
Crescent: less than
half lit (crescent roll)
Gibbous: more than
half lit

Quarter: half lit
Synchronous rotation: rate of
orbit and rotation equal…see
same side of moon
 Sidereal month: 360° orbit of
M around E, 27.3d
 Lunar month: new moon to
new moon, 29.5 d
 Moonrise 50 min later each
day b/c E has to turn an
additional 13°

Moon’s orbit creates
tides…GRAVITATIONAL
PULL OF MOON ON EARTH
 Modeling Moon’s Motions
Activity

Tides:
 Locally 2 high, 2 low per day
 Spring tides: (straight)
 higher highs & lower lows
 SunMoonEarth are aligned
 Full moon or new moon
 Neap tides: (ninety degree angle)
 Tides less dramatic-weaker
 Quarter moons
 Sun/Moon cancel out/< they’re
@
 Since the water is always moving, the
Earth cannot hold onto it, and the
moon is able to pull at it.
 The ocean is constantly moving from
high tide to low tide, and then back to
high tide. There is about 12 hours and
25 minutes between the two high
tides. (Locally 2 high, 2 low per day)

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Moon blocks Sun from
our view
 Total: entirely blocked
 Partial: portion blocked
 Penumbra: shadowy
region cast by moon
 Umbra: darkest shadow
cast by moon, coneshaped

See pg. 783: moon’s
ecliptic plane

Moon passes through
Earth’s shadow
 Umbra: darkest shadow
behind Earth…ultra dark
 Penumbra: shadowy area
cast behind Earth…partly
 Total lunar eclipse: entire
M in E’s shadow
 Partial lunar eclipse:
partial shadow of E on M