Chapter 28 Vocab
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Satellite
Moon
Anorthosites
Mare
Craters
Rays
Rilles
Regolith
Breccia
Giant impact
hypothesis
Barycenter
Apogee
Perigee
Eclipse
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
Umbra
28.
Penumbra
29.
Solar eclipse
30.
Partial solar
eclipse
31.
Annular eclipse
32.
Lunar eclipse
33.
Partial lunar
34.
eclipse
Penumbral eclipse 35.
New moon
36.
Waxing moon
37.
Waxing gibbous 38.
phase
39.
Full moon
40.
Waning moon
Waning gibbous
phase
Earthshine
Galilean moons
Asteroids
Asteroid belt
Trojan asteroids
Near-Earth
asteroids
Comets
Kuiper Belt
Oort Cloud
Meteoroids
Meteor
Meteorite
I.
Earth’s Moon
A. Exploring the Moon
1. Satellite: natural or artificial body that orbits a larger body
2. Moon: natural satellites orbiting larger bodies
3. US’s Apollo program sent 6 spacecraft to moon between 19691972
a. Moon’s gravity is 1/6 of the gravity on Earth, which affects weight
b. Since gravity is weak, moon doesn’t have an atmosphere
c. Traveling on the moon requires special vehicles, and bouncing is more
effective (& probably more fun) than walking
d. Surface temp varies from 134 C to -170 C (273 F to -274 F)
B. Lunar Features
1. Anorthosites (light areas) & maria (dark areas)
2. Craters were formed from impacts with debris left over from
formation of solar system ~ 4 bya
3. Rilles: long, deep channels running through maria; thought to be
leftover lava channels from maria formation
4. Regolith: layer of dust & rock that covers moon; formed from
meteorite impacts crushing existing lunar rock
5. Lunar rocks are similar to Earth’s – all lunar rocks are igneous
a. Same element, different proportions
b. Surface rocks: silicon & oxygen
c. Highland rocks: calcium & aluminum
d. Maria rocks: basaltic, contain titanium, magnesium, & iron
e. Breccia: present in maria & highland rock; contains fragments of rocks
fused together
C. Moon’s Interior
1. Layered like Earth’s with crust, mantle, &
core
2. Crust
a. Far side (facing away from Earth) has
thicker crust (100km), mostly mountains
with a few small maria
b. Near side (facing Earth) has 60km thick
crust
3.
Mantle & Core
a. Mantle is largest region of moon, composed
of silica, magnesium, & iron
b. Scientists think the core is composed of iron &
isn’t completely solid or liquid
D. Moon Formation
1. Occurred in 3 stages:
a. Giant Impact Hypothesis: Mars-sized body struck Earth early in
formation of solar system & ejected chunks of mantle into orbit, which
clumped together to form the moon
b. Differentiation occurred, with denser material moving toward the
center of the moon & forming a small core; less dense materials
formed the crust
c. Meteorites bombarded the moon, forming the cratered surface it has
today
d. Meteorite impacts caused lava flows, which formed maria – but
scientists are uncertain how magma formed on the moon
II. Movements of the Moon
A. Earth-Moon System
1. If you look at the moon from space, it rotates on its axis once
every 27.3 Earth days
a. But from the moon’s surface, the time from sunrise to sunrise is 29.5
Earth days
b. This discrepancy is a result of the fact that the moon is revolving
around the Earth while both revolve around the sun
c. Looking from space, the Earth and the moon actually orbit each other,
and orbit the sun as a single system
d. Barycenter: balance point of the Earth-moon system; located inside of
the Earth because the moon’s mass is 1/80 of Earth’s
2.
Moon’s Orbit
a. Orbits Earth in an ellipse
b. Apogee: point at which the moon is farthest from Earth
c. Perigee: point at which the moon is closest to Earth
3. Moon appears to rise & set on Earth’s horizon, which it does – but
if you look at the timing, it actually rises & sets 50 minutes later
each night
a. This is due to Earth’s rotation & the moon’s revolution
b. It takes 50 minutes for our horizon to catch up to the moon
B. Eclipses
1. Occur when one celestial body passes through the shadow of
another
2. Shadows cast by Earth & the moon have 2 parts:
Umbra: inner cone-shaped part; sunlight is totally blocked
Penumbra: outer part; sunlight is partially blocked
a.
b.
3.
Solar Eclipses
a. Moon between sun & part of Earth, so the moon’s shadow falls on
Earth
b. Total solar eclipse: sun is completely blocked by moon; the umbra of
the moon is on the part of the Earth that’s in line with the moon & sun
i.
ii.
iii.
Moon’s penumbra is very small, so a total solar eclipse only occurs on a
small part of Earth & is only seen by people in that area
Never lasts more than 7 minutes in any location
Next in U.S. will be in 2017
c. Effects of Solar Eclipses
i. Diamond-ring effect: last bits of sunlight before sun is completely blocked
out – forms a ring around the moon as it covers the sun
ii. Annular eclipse: sun is not completely blocked out – there is always a thin
ring of sunlight visible around the moon
Lunar Eclipses
4.
a. Earth between moon & sun, so Earth’s shadow crosses lighted portion
of moon
b. Total lunar eclipse: entire moon in Earth’s umbra
i.
ii.
5.
Partial lunar eclipses occur when only part of the moon is in Earth’s umbra
Penumbral eclipse: entire moon in Earth’s penumbra; moon darkens very
little, so eclipse is barely noticeable
Eclipse Frequencies
a.
b.
May be up to 7 eclipses during a calendar year
Total eclipses are unusual because it is rare for all three objects
(Earth, moon, and the sun) to line up perfectly
C. Phases of the Moon
1. Shape of the moon varies depending on its position relative to
Earth and the sun – these are the moon’s phases
2. New moon: when moon is directly between sun & Earth; light from
the sun hits the far side of the moon, so we do not see any light
3. Waxing: size of the lighted portion of the moon increases
a.
b.
c.
Waxing-crescent phase: sliver of near side is illuminated
First-quarter phase: half of the moon is illuminated as waxing moon
becomes a semicircle; occurs after one-quarter of its orbit has passed
Waxing-gibbous: more than half of the moon’s near side is illuminated;
moon continues to wax until it’s a full circle
Full moon: Earth is between sun & moon; entire near side is
illuminated!
Waning: size of the lighted portion of the moon decreases
4.
5.
a.
b.
c.
d.
Waning-gibbous: moon is waning but there is still more than half of
the near side illuminated
Third-quarter phase: half of the moon is illuminated as waning moon
becomes a semicircle; occurs after three quarters of its orbit has
passed
Waning-crescent phase: sliver of near side is illuminated
After waning-crescent, the moon is between the Earth & sun again,
and it’s another new moon!
D. Tides
1. Tidal bulges are formed as a result of the moon’s gravitational pull
on Earth, which decreases as the moon is further away from Earth
2. The ocean on the side of Earth nearest to the moon is pulled with
more force, causing “bulges” on the both sides
3. These bulges change throughout the day since Earth rotates,
which causes the tides!
4. Twice per month, we have high tides when the Earth, moon, and
sun are almost in line
• Copy Figure 8 on p. 796
• p. 798 #1-11