In this presentation we will discuss the following:

1
(No Transcript)
2
In this presentation we will discuss the
following Orbital Mechanics Phases of the Moon
Eclipses Tides
3
ORBITAL MECHANICS
4
The orbit of the Moon is tilted about 5 degrees
relative to the orbit of the Earth around the Sun
(the ecliptic).
5
The ascending node begins when the Moon crosses
north of the ecliptic.
The descending node begins when the Moon crosses
south of the ecliptic.
6
(No Transcript)
7
MOTION When viewed from above the North Pole, the
Earth is revolving counter-clockwise around the
Sun. The Moon is revolving counter-clockwise arou
nd the Earth.
8
(No Transcript)
9
The revolution (orbital motion) of the Moon takes
the same amount of time as the rotation (axial
motion). Because of this, the same side of the Mo
on always faces the Earth. Phases occur on the F
ar-side of the Moon, we just cant see them from
Earth.
10
The red spot represents a stationary position on
the Moon.
Since rotation revolution, one side of the Moon
always faces the Earth.
11
Shape of the Moons Orbit The orbit is an ellipse
, not a perfect circle. Because of this, the
distance to the Moon is not always the same.
12
Perigee 356,375 Km
Apogee 406,720 Km
13
Because of the difference in distance the moon is
larger at Perigee and smaller at Apogee.
14
Perigee Apogee
15
Lunar Librations In addition to the elliptical or
bit, the Moon wobbles during its revolution
around the Earth. These wobbles are called
librations.
16
Although the same side of the Moon always faces
us, because of librations, we can see almost 60
of the Moons surface over time.
17
PHASES OF THE MOON
18
The phases of the Moon are caused by the relative
positions of the Moon, Earth, and Sun in the sky.
The shadow of the Earth DOES NOT have any effect
on the phases. The only time the shadow of the E
arth effects the appearance of the Moon is during
an eclipse.
19
TERMINOLOGY Waxing - Increasing or to grow larger
Waning - Decreasing or to become smaller Gibbou
s - Bulging or convex shaped. More than half.
Crescent - Concave shaped. Less than half.
20
New Moon - The Moon's unilluminated side is
facing the Earth. The Moon is not visible (except
during a solar eclipse).

21
The New Moon occurs when the Sun and Moon are
quite close together in the sky.

22
(No Transcript)
23
Waxing Crescent - The Moon appears to be partly
but less than one-half illuminated by direct
sunlight. The fraction of the Moon's disk that is
illuminated is increasing.
24
First Quarter - One-half of the Moon appears to
be illuminated by direct sunlight. The fraction
of the Moon's disk that is illuminated is
increasing.
25
First Quarter occurs when the Sun and Moon are
about 90 degrees apart in the sky. In fact, this
"half Moon" phases is called First Quarter
because it occurs when the Moon is one-quarter
of the way around the sky along its orbit from
New Moon.
26
(No Transcript)
27
Waxing Gibbous - The Moon appears to be more than
one-half but not fully illuminated by direct
sunlight. The fraction of the Moon's disk that is
illuminated is increasing.
28
Full Moon - The Moon's illuminated side is facing
the Earth. The Moon appears to be completely
illuminated by direct sunlight.

29
Full Moon occurs when the Sun and Moon are at
nearly opposite positions in the sky - which is
why a Full Moon rises about the time of sunset,
and sets about the time of sunrise, for most
places on Earth.
30
(No Transcript)
31
Waning Gibbous - The Moon appears to be more than
one-half but not fully illuminated by direct
sunlight. The fraction of the Moon's disk that is
illuminated is decreasing.
32
Last Quarter - One-half of the Moon appears to be
illuminated by direct sunlight. The fraction of
the Moon's disk that is illuminated is
decreasing.
33
Like First Quarter, Last Quarter occurs when the
Sun and Moon are about 90 degrees apart in the
sky. This "half Moon" phase is called Last
Quarter because it occurs when the Moon is
three-quarters of the way around the sky along
its orbit from New Moon.
34
(No Transcript)
35
Waning Crescent - The Moon appears to be partly
but less than one-half illuminated by direct
sunlight. The fraction of the Moon's disk that is
illuminated is decreasing.
36
Following waning crescent is New Moon, beginning
a repetition of the complete phase cycle of 29.5
days average duration. The time in days counted
from the time of New Moon is called the Moon's
"age". Each complete cycle of phases is called a
"lunation".
37
Because the cycle of the phases is shorter than
most calendar months, the phase of the Moon at
the very beginning of the month usually repeats
at the very end of the month.
38
And what is the line between the light and dark
side of the Moon called?
39
THE TERMINATOR
40
TERMINATOR
41
ECLIPSES
Lunar eclipse 1/2000 By Steve Bell
42
The word eclipse means to obscure or darken.
There are two types of eclipses lunar and
solar. A lunar eclipse is when the Moon is obscur
ed or darkened by the Earth. A solar eclipse is w
hen the Sun is obscured or darkened by the Moon.
43
LUNAR ECLIPSES Lunar eclipses occur only around t
he Full Moon when the Moon is in the shadow of
the Earth. The Earths shadow has two regions th
e penumbra and the umbra. The penumbra is a parti
al shadow and the umbra is a complete shadow.
44
(No Transcript)
45
LUNAR ECLIPSE TYPES Penumbral Lunar EclipseOccur
s when the moon passes through the Earths
Penumbral shadow. These eclipses are difficult
to observe. Partial Lunar EclipseOccurs when a p
ortion of the Moon passes through the Earths
umbral shadow.
46
Total Lunar Eclipse Occurs when the entire Moon p
asses through the Earths umbral shadow. These
are the most vibrant eclipses. The Moon takes
on a bright orange or red color during a Total
Lunar Eclipse. TOTALITY is the phase when the ent
ire Moon is within the shadow.
47
(No Transcript)
48
TOTAL LUNAR ECLIPSE
49
SOLAR ECLIPSE A solar eclipse occurs only at or
near the New Moon when the Earth is in the Moons
shadow. Like the Earths shadow in a lunar ecli
pse, the Moons shadow has two distinct parts
The penumbra and the umbra.
50
(No Transcript)
51
SOLAR ECLIPSE TYPES Total Solar EclipseOccurs wh
en the umbra of the Moon's shadow touches a
region on the surface of the Earth.
Partial Solar EclipseOccurs when the penumbra of
the Moon's shadow passes over a region on the
Earth's surface.
52
Annular Solar Eclipse Occurs when a region on
the Earth's surface is in line with the umbra,
but the distances are such that the tip of the
umbra does not reach the Earth's surface.
53
(No Transcript)
54
TOTAL SOLAR ECLIPSE
55
TOTAL SOLAR ECLIPSES Eclipses appear in the mytho
logy of different cultures as symbols of fear
and the overthrow of the natural order.
Only in more recent times have they been viewed
strictly as an explainable astronomical events.

56
The eclipse begins with a partial phase in which
the Moon gradually covers more and more of the
Sun. This progression always goes from right to
left.
57
As totality approaches an eerie twilight begins.
In the final moment before totality light shining
through the valleys of the moon gives the
impression of beads called Baileys Beads. Solar
prominences and flares often become visible at
this time.
58
Baileys Beads
59
The last flash of light from the surface of the
Sun creates an effect known as the diamond ring
effect.
60
Diamond Ring Effect
61
During totality the corona comes into view. The
corona is a million times fainter than the
surface of the Sun and is only visible during a
total eclipse.
62
CORONA
63
Solar Prominences and Flares
64
TIDES
65
Tides are the bulging of large bodies of water
caused by the Moons gravitational pull.
Water bulges on the side of the Earth nearest the
Moon and on the opposite side of the Earth.
66
The bulge on the side of the Earth near the moon
is caused by the gravitational pull of the Moon.
The atmosphere and the Earth itself also bulge
but to a lesser extent. The bulge on the opposite
side of the Earth is caused by the centrifugal
force of the Earth and Moons rotation.
67
We usually describe the Moon as revolving around
the Earth, however, in reality the Earth and
Moon rotate around a common center of gravity
called the barycenter. The barycenter is located
about 1000 miles below the surface of the Earth.
68
Because of this, centripetal force exists on the
side of the Earth opposite the moon causing the
bulge.
69
BARYCENTER
70
Effect of the Earths Rotation
The yellow line marks a point on the surface of
the Earth that is currently at low tide.
71
Since the Earth is rotating, six hours later the
point marked by the line will be at high tide.
72
Larger bodies of water have greater tides. Ocean
tides range from one to several feet.
Since the Great Lakes are much smaller then the
oceans, tides are much smaller less than an
inch.
73
The difference in the water level between high
and low tide is also influenced by the Sun and by
the geologic shape of the ocean bottom and coast
line.
74
Tides are greatest during the New Moon and Full
Moon when the Sun and Moon are in line with each
other. These are called spring tides because of t
he way the water springs up.
75
Tides at First and Last Quarter are much less and
are called neap tides. When the geologic structur
e of the coast forms a funnel the height of the
tide is greatly increased.
76
The greatest tides on Earth take place in the Bay
of Fundy in New Brunswick, Canada.
These tides can be as high as 50 feet.
The tide comes in with such force that a 3 foot
high wave called the tidal bore precedes high
tide.
77
(No Transcript)
78
Bay of Fundy - Low tide
79
Bay of Fundy High tide