Transcript Atmospheres Interiors and the Surface of the Moon

The Moon
Atmosphere?
 There
is none!
 The gravity of the Moon is too low
to hold on to the molecules of an
atmosphere.
 There is water on the moon
though—ice at the poles.
Interior
 Mostly
made of relatively low
density materials
 Has a small, solid core that is also
low density
 The crust on the far side of the
Moon from the Earth is thicker,
because the mantle and core
were pulled towards Earth by
gravity.
Lunar Surface
 Maria:
large, roughly circular
dark areas caused by the flow of
lava when the Moon was still
volcanic.
 Made
of basalt—a dark colored,
high density rock from the Moon’s
mantle
Lunar Surface
 Lunar
highlands: light colored
areas elevated several kilometers
above the maria.
 Made
of rocks that are light in color,
rich in aluminum, and low density
 Probably part of the original lunar
crust—thrust up by the impact of
meteoroids
Cratering
 Impact
craters are created when
meteoroids, asteroids, and
comets strike the moon
 The
crater is usually about 10 times
the diameter of the impactor
 This is the only form of erosion on
the Moon—it creates a thick layer of
dust known as the regolith
Cratering
 Two
crater types:
Simple crater—small and deep
with smooth bowl shape
Complex crater—large, shallow,
with central peak
The Moon’s Origin

Before the Apollo missions in the
1960’s and 70’s, there were
three leading theories to the
moon’s origin:
1. The Earth’s gravity captured it.
2. The Moon and the Earth
condensed from the same
cloud of dust
3. When it is still molten, a
large object strikes the
Earth. (Impact Theory)
 Material from both objects
flies off.
 That material condenses
and forms the moon
The general
locations and
orientations
for the
phases of the
moon.
Phases of the Moon
(7) Third Quarter
Sunlight
Sunlight
(6) Waning
Gibbous
(8) Waning
Crescent
Earth
(1) New Moon
Earth spins on its
axis in the same (2) Waxing
direction as the
Crescent
moon’s orbit.
(5) Full Moon
(4) Waxing
Gibbous
(3) First Quarter
Perspective & The Moon’s Face
How much of the
moon’s face does the
person see?
Sunlight
Sunlight
NEW MOON
Wherever the
person looks all
they see is
shadowed moon.
Earth
(1)
New Moon
What time of day is
it for the observer?
Noon!!
Perspective & The Moon’s Face
How much of
the moon’s
face does the
person see?
Sunlight
Earth
Sunlight
WAXING
CRESCENT When
you look up you
see only a small
crescent brightly lit.
(Right Side)
(2)
Waxing Crescent
What time of
day is it for
the observer?
3PM!!
Perspective & The Moon’s Face
How much of
the moon’s
face does the
person see?
Sunlight
What time of day is
it for the observer?
Sunset - 6PM!!
Earth
Sunlight
FIRST QUARTER When
you look up you see one
half of the front face of the
Moon brightly lit. (Right
side)
(3)
First Quarter
Perspective & The Moon’s Face
How much of the
moon’s face does
the person see?
Sunlight
Earth
Sunlight
WAXING GIBBOUS
When you look up you
see only a small crescent,
darkly shadowed, on the
left.
(4)
Waxing Gibbous
What time of day is
it for the observer?
9PM!!
Perspective & The Moon’s Face
How much of the
moon’s face does
the person see?
Sunlight
Earth
Full
Moon
(5)
Sunlight
FULL MOON When
you look up you see
the entire face of the
Moon brightly lit.
What time of day is
it for the observer?
Midnight-12AM!!
Perspective & The Moon’s Face
How much of the
moon’s face does
the person see?
Sunlight
(6)
Waning Gibbous
Earth
Sunlight
WANING GIBBOUS
When you look up you
see only a small crescent,
darkly shadowed, on the
right.
What time of day is
it for the observer?
3AM!!
Perspective & The Moon’s Face
How much of the
moon’s face does
the person see?
(7)
Third Quarter
Sunlight
Sunlight
THIRD QUARTER
When you look up you
see one half of the
front face of the Moon
brightly lit. (Left side)
Earth
What time of day is
it for the observer?
Sunrise - 6AM!!
Perspective & The Moon’s Face
How much of the
moon’s face does
the person see?
Waning
Crescent
(8)
Sunlight
Sunlight
WANING CRESCENT
When you look up you
see only a small crescent
brightly lit. (Left Side)
Earth
What time of day is
it for the observer?
9AM!!
Eclipses
 Although
the Sun is about 400
times larger than the Moon, it is
also about 400 times further
away.
 As a result of this coincidence,
the Moon can completely cover
the Sun, producing a total solar
eclipse.
Eclipses
 The
shadow of any body consists
of two parts:
The umbra is the darkest part of
the shadow--in the center.
The penumbra a lighter
shadow—on the outer edges.
Total Solar Eclipse
Penumbra
Umbra
Solar Eclipse
 A total
solar eclipse occurs about
once every 18 months
somewhere in the world.
 At any given location, a total solar
eclipse occurs once every 360
years.
The next total solar eclipse in
the U.S. is on Aug. 21 2017.
Total
Solar
Eclipse
Solar Corona During Eclipse
Total Solar Eclipse
 As
the Moon orbits the Earth, its
apparent size varies.
Only when the Moon is closest
to the Earth can it completely
block the Sun.
If the Moon does not completely
cover the Sun we get an
annular eclipse.
Lunar Eclipses
 A lunar
eclipse occurs when the
Moon passes into the shadow of
the Earth.
 The lunar eclipse is visible to
everyone on the night side of the
Earth.
Lunar Eclipse
Lunar Eclipse
NASA Eclipse Page
 The
best web page on eclipses is:
 http://sunearth.gsfc.nasa.gov/ecli
pse/eclipse.html
One reason we know the Earth is
round:
 Early
scientists determined that
the Earth was round, because
they recognized that its shadow
was being cast on the moon
during a lunar eclipse.
 The
shadow is curved.
The Tides
 12-hour cycle
Slide 32
Caused by
the
difference of
the Moon’s
gravitational
Excess
Excess gravity
centrifugal attraction on
pulls
forcewater
pushes water the water on
towards
thethe
moon Earth
away from
on
the on
near
moon
theside
far
side
Spring and Neap Tides
•The Sun is also producing tidal
effects.
Spring tides
•Near Full and New Moon, the
Sun’s gravity combines with the
moon’s gravity to cause spring
tides.
Neap tides
Slide 33
Spring and Neap Tides
• Near first and third quarter,
Sun and Moon’s gravity are
at a right angle, causing
neap tides.
Slide 34
Effects of tides
• Slow down the rotation of earth
•Friction slows down the rotation
• The day was 18 hours long 900
mya
Slide 35
The Tidally-Locked Orbit of
the Moon
Earth exerts
Ittidal
is rotating
forces
on the
with
the
same
This
is why
moon’s
period
around
we always
rocky
its
axis
as
it is
see
the
same
interior
that
orbiting
Earth
side
of
the
slow down
(tidally
Moon.
its rotation.
locked).
Slide 36
Acceleration of the Moon’s
Orbital Motion
Gravitational force pulls the moon
slightly forward along its orbit.
Slide 37