Moon Phases: The moon's phases refer to the different appearances of the moon as observed from Earth during its orbit around our planet. These phases are primarily determined by the relative positions of the Earth, the moon, and the sun. As the moon orbits the Earth, different portions of its surface are illuminated by sunlight, resulting in the various phases we observe. 1. New Moon: The new moon occurs when the moon is positioned between the Earth and the sun, with its illuminated side facing away from Earth. From our perspective, the moon appears dark and invisible in the night sky. This marks the beginning of a new lunar cycle. 2. Waxing Crescent: Following the new moon, a small sliver of the moon becomes visible as sunlight gradually illuminates its surface. This phase is known as the waxing crescent. It appears as a thin crescent shape in the western sky after sunset. 3. First Quarter: During the first quarter phase, the moon has completed approximately one-quarter of its orbit around the Earth. Half of the moon's surface is illuminated by sunlight, creating a half-moon shape. This phase is often referred to as the waxing half or the half moon. 4. Waxing Gibbous: As the moon continues to orbit, more of its surface becomes illuminated by sunlight. The waxing gibbous phase occurs when the illuminated portion of the moon is greater than half but not yet full. It appears as a bulging, almost full moon in the night sky. 5. Full Moon: The full moon occurs when the Earth is positioned directly between the sun and the moon, with the moon's entire illuminated side facing Earth. This phase marks the midpoint of the lunar cycle and is characterized by a fully illuminated, round shape. The full moon is often associated with cultural and religious significance and is the brightest phase of the lunar cycle. 6. Waning Gibbous: Following the full moon, the moon begins to wane or decrease in illumination. The waning gibbous phase occurs when the illuminated portion of the moon is greater than half but gradually diminishing. It appears as a shrinking, nearly full moon in the night sky. 7. Third Quarter: During the third quarter phase, the moon has completed approximately three-quarters of its orbit around the Earth. Half of the moon's surface is illuminated, but this time, the opposite half compared to the first quarter phase. It is often referred to as the waning half or the half moon. 8. Waning Crescent: The waning crescent phase marks the final stage of the lunar cycle before the new moon. Only a small portion of the moon's surface is illuminated by sunlight, appearing as a thin crescent shape in the eastern sky before sunrise. This phase gradually transitions into the new moon, completing the lunar cycle. These phases repeat in a continuous cycle, with each complete cycle lasting approximately 29.5 days, known as a synodic month. The moon's phases have significant cultural, religious, and scientific importance,

1. MOON

2. MOON
After the Sun, the Moon is the brightest
and most obvious object in the sky.
Unlike the Sun, it does not shine under its
own power, but merely glows with
reflected sunlight

3. MOON
C
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Moon starting dark and getting more and more
illuminated by sunlight over the course of about two
weeks. After the Moon’s disk becomes fully bright, it
begins to fade, returning to dark about two weeks later.

4. MOON PHASES ANDECLIPSE

5. LearningObjectives
At the end of the lesson, student must be able to:
Identifies the different phases of the moon
Describe lunar eclipse and solareclipse

6. P
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E
S
The moon appears to change shape a little bit every
night.

7. The moon orbits around the Earth, much like the Earth orbits the sun.
However, while the Earth takes about 365 days to travel once around the
sun - one year - the moon completes its orbit around the Earth in only 29
and a half days - or about one month. That's actually where the idea of
months came from - the time it takes for the moon to complete one orbit
around the Earth - and the words 'moon' and 'month' come from the same
root.
The word “moon” shares its origins with the Latin word metri, which means
“to measure,” and mensis, which means “month.” The Moon is called the Moon
because it is used to measure the months.
Why this thinghappens?

8. Despite how bright it looks in the sky; the moon does not have any light of
its own. It only appears to shine brightly in the sky because light from the
sun hits it and bounces off. Justlike the Earth, the moon has a day side and a
night side, with half of it in sunlight and half of it in darkness at any one
time.
As the moon travels through its orbit around the Earth, that dividing line
between day and night, called the terminator, is visible from different angles,
giving the impression that different amounts of the moon are lit up on
different days.

9. The appearance of the Moon changes over the course of a complete monthly cycle. The
pictures of the Moon on the white circle show the perspective from space, with the Sun off
to the right in a fixed position. The outer images show how the Moon appears to you in the
sky from eachpoint in the orbit.

10. N
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The new moon is barely visible and occurs when the Earthand moon
are aligned and the sun and earth are on opposite sides of the moon.
The Moon is said to be new when it is in the same general direction in the sky as the Sun(position
A). Here, its illuminated (bright) side is turned away from us and its dark side is turned toward us.
In this phase, the Moon is invisible to us; its dark, rocky surface does not give off any light of its
own. Because the new moon is in the same part of the sky as the Sun, it rises at sunrise and sets at
sunset.

11. W
A
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G
C
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C
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Awaxing crescent moon occurs wften tfte moon begins to
become visible again after a NewMoon.
After a few days, once the moon has moved along a little in its orbit, we can begin to see some of
the moon's day side from Earth. What we see is just a thin slice of light, called a crescent. We call it
a 'waxing crescent,' because 'waxing' means 'growing.'

12. F
I
R
S
TQ
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Tfte first quarter moon occurs wften tfte moon reacftes tftefirst
quarter of its orbit around tfteeartft.
The first quarter moon is sometimes called the half moon because it appears to us that half of
the moon is illuminated, but it is called 'first quarter' because the moon is one-quarter of the
way through itscycle.

13. W
A
X
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GG
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B
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A waxing gibbous moon means tfte visibility of tfte moon is
getting bigger. It is bigger tftan a semicircle but smallertftan a
full moon.
As days pass, the moon continues to grow, soon entering its next phase, the waxing gibbous.
Gibbous means 'humped' or 'swollen,' and again, we call it waxing because it grows thicker
every night

14. F
U
L
L
M
O
O
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Tfte full moon is visible wften tfte moon is on tfte opposite sideof
Eartft tftan tfte sun.
Afull moon is the biggest, brightest, and easiest phase of the moon to see. The moon rises at
sunset and is up allnight
During a full moon is the only time that a lunar eclipse can happen, because that is the only
time that the Earth's shadow could fall on the moon.

15. W
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G
G
I
B
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A waninggibbous moon comes after tfte Full Moon. Tfte amount of
moon visible begins to decrease. More tftan ftalf of tfte moon isstill
visible.
As the moon continues in its path, it appears to shrink again as we begin to see more and more
of its dark side.Afew days after the full moon the moon will be a gibbous again, but this time
it's a waning gibbous. 'Waning' means shrinking, or getting smaller, and so the moon will be
waning for the rest of its orbit.

16. T
H
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D
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E
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Tfte tftird quarter moon is tfte opposite view of tfte FirstQuarter
moon. It looks like ftalf of a moon but remember tfte moon is a
spftere.
This phase is another half moon, but this time it's called 'third quarter' or sometimes 'last' or
'final' quarter, because the moon is three-quarters of the way through its orbit.

17. W
A
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G
C
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E
S
C
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N
T
A waning crescent moon ftas less tftan ftalf oftfte moon still visible.
After half moon, it will shrinks into a waning crescent, which will continue to shrink night
after night until it vanishes completely into the next new moon.

18. Note that there is one thing quite misleading about this figure. If you look at the Moon in position E,although it is full in theory,
it appears as if its illumination would in fact be blocked by a big fat Earth, and hence we would not see anything on the Moon
except Earth’s shadow. In reality, the Moon is nowhere near as close to Earth (nor is its path so identical with the Sun’s in the
sky) as this diagram (and the diagrams in most textbooks) might lead you to believe.
The Moon is actually 30 Earth-diameters away from us; Science and the Universe: A Brief Tour contains a diagram that shows
the two objects to scale. And, since the Moon’s orbit is tilted relative to the path of the Sun in the sky, Earth’s shadow misses the
Moon most months. That’s why we regularly get treated to a full moon. The times when Earth’s shadow does fall on the Moon
are called lunareclipses.

19. D
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H
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E
K
The week seems independent of celestial motions, although its length may have been based on the time
between quarter phases of the Moon. In Western culture, the seven days of the week are named after the
seven “wanderers” that the ancients saw in the sky: the Sun, the Moon, and the five planets visible to the
unaided eye (Mercury, Venus, Mars, Jupiter,andSaturn).
In English, we can easily recognize the names Sun-day (Sunday), Moon-day (Monday), and Saturn-day
(Saturday), but the other days are named after the Norse equivalents of the Roman gods that gave their
names to the planets. In languages more directly related to Latin, the correspondences are clearer.
Wednesday, Mercury’s day, for example, is mercoledi in Italian, mercredi in French, and miércoles in
Spanish. Mars gives its name to Tuesday (martes in Spanish), Jupiter or Jove to Thursday (giovedi in
Italian), and Venus to Friday (vendrediin French).

20. Video Presentation of Moon Phases

21. Activity about the Phases ofMoon
Back to Back DrawingCommunication

22. T
h
eMoon’sRevolutionandRotation
The Moon orbits eastward around Earth in 27.3 days, the Moon's sidereal period. This is how long the
Moon takes to circle the sky once and return to the same position relative to the stars.
A complete cycle of lunar phases takes 29.5 days, the Moon's synodic period. (Synodic comes from the
Greek words for"together and "path")
The difference results from Earth’s motion around the Sun. The Moon must make more than a complete
turn around the moving Earth to get back to the same phase with respect to the Sun. As we saw, the
Moon changes its position on the celestial sphere rather rapidly: even during a single evening, the Moon
creeps visibly eastward among the stars, traveling its own width in a little less than 1hour. The delay in
moonrise from one day to the next caused by this eastward motion averages about 50 minutes.

23. Video Presentation
Sidereal &Synodic

24. W
hyMoonalwayskeepthesamefaceturnedtowardEarth?
The Moon rotates on its axis in exactly the same time that it takes to revolve about Earth.As a consequence, the
Moon always keeps the same face turned toward Earth and this situation is known as tidal locking.
If the Moon did not rotate as it orbited Earth, it would present all of its sides to
our view
The Moon rotates in the same period that it revolves, so we always see the same
side

25. Video Presentation
Tidal locking

26. C
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One of the coincidences of living on Earth at the present time is that the two most prominent
astronomical objects, the Sun and the Moon, have nearly the same apparent size in the sky. Although the Sun
is about 400 times larger in diameter than the Moon, it is also about 400 times farther away, so both the Sun
and the Moon have the same angular size—about 1/2°. As a result, the Moon, as seen from Earth, can appear to
cover the Sun,producing one of the most impressive events in nature.
Any solid object in the solar system casts a shadow by blocking the light of the Sun from a region
behind it. This shadow in space becomes apparent whenever another object moves into it. In general, an
eclipse occurs whenever any part of either Earth or the Moon enters the shadow of the other. When the
Moon’s shadow strikes Earth, people within that shadow see the Sun at least partially covered by the Moon;
that is, they witness a solar eclipse. When the Moon passes into the shadow of Earth, people on the night side
of Earth see the Moon darken in what is called a lunar eclipse.

27. Illustrates the appearance of the Moon’s shadow and what the Sun and Moon would look like from different
points within theshadow.
The shadows of Earth and the Moon consist of two parts: a cone where the shadow is darkest, called the
umbra, and a lighter, more diffuse region of darkness called the penumbra. As you can imagine, the
most spectacular eclipses occur when an object enters the umbra

28. The shadow cast by a map tack can be used to understand the shadows of Earth and the Moon.
The umbra is the region of total shadow; the penumbra is the region of partial shadow.

29. (a) The shadow cast by a spherical body (the Moon, for example) is shown. Notice the dark umbra and
the lighter penumbra. Four points in the shadow are labeled with numbers.
In (b) you see what the Sunand Moon would look like in the sky at the four labeled points.At position 1,
you see a total eclipse.At positions 2 and 3, the eclipse is partial.At position 4, the Moon is farther away
and thus cannot cover the Suncompletely; a ring of light thus shows around the Sun,creating what is
called an “annular”eclipse.

30. The umbra is the portion of
the Moon's shadow where the
Moon completely covers the
Sun. This is when the Total
Solar Eclipse occurs,where
you cannot see theSunat all.
Antumbra is the area beyond the
umbra. Here, the Moon is
completely in front of the Sun,
but doesn't cover the entire Sun.
The outline of the Sun can be
seen around the shadow of the
Moon.
And that is when you see the
Annular Solar Eclipse.
Penumbra is the area of the
shadow where only a portion
of the Moon is in front of the
Sun. This is when the Partial
Solar Eclipse occurs,which let's
you see only a part of the Sun.

31. If the path of the Moon in the sky were identical to the path of the Sun (the ecliptic), we might
expect to see an eclipse of the Sun and the Moon each month—whenever the Moon got in
front of the Sun or into the shadow of Earth. However, as we mentioned, the Moon’s orbit is
tilted relative to the plane of Earth’s orbit about the Sun by about 5° (imagine two hula hoops
with a common center, but tilted a bit). As a result, during most months, the Moon is
sufficiently above or below the ecliptic plane to avoid an eclipse. But when the two paths
cross (twice a year), it is then “eclipse season” and eclipses are possible.

32. The apparent or angular sizes of both the Sunand
Moon vary slightly from time to time as their
distances from Earthvary.

33. E
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Much of the time, the Moon looks slightly smaller than the Sunand cannot
cover it completely, even if the two are perfectly aligned.
If the Moon crosses in front of the Sunwhen the Moon's disk is smaller in
angular diameter than the Sun's, it produces an annular eclipse, a solar eclipse
in which a ring (or annulus) of light is visible around the disk of the Moon.
In this type of “annular eclipse,” there is a ring of light around the dark sphere
of theMoon.
Annular Eclipse

34. E
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If an eclipse of the Sunoccurs when the Moon is somewhat nearer than its
average distance, the Moon can completely hide the Sun, producing a total solar
eclipse. Another way to say it is that a total eclipse of the Sunoccurs at those
times when the umbra of the Moon’s shadow reaches the surface of Earth.
Total Solar Eclipse

35. E
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Total Solar Eclipse
The geometry of a total solar eclipse is illustrated in this figure. If the Sunand
Moon are properly aligned, then the Moon’s darkest shadow intersects the
ground at a small point on Earth’s surface. Anyone on Earthwithin the small
area covered by the tip of the Moon’s shadow will, for a few minutes, be unable
to see the Sunand will witness a total eclipse.

36. E
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SO
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At the same time, observers on a larger area of Earth’s surface who are in the
penumbra will see only a part of the Sun eclipsed by the Moon: we call this a
partial solar eclipse.
Partial Solar Eclipse

37. E
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Between Earth’s rotation and the motion of the Moon in its orbit, the tip of the Moon’s
shadow sweeps eastward at about 1500 kilometers per hour along a thin band across the
surface of Earth.The thin zone across Earthwithin which a total solar eclipse is visible
(weather permitting) is called the eclipse path. Within a region about 3000 kilometers on
either side of the eclipse path, a partial solar eclipse is visible. Itdoes not take long for the
Moon’s shadow to sweep past a given point on Earth.The duration of totality may be only a
brief instant; it can never exceed about 7minutes.

38. https://www.obliquity.com/skyeye/misc/eclipse.html

39. AppearanceofaTotalEclipse
What can you see if you are lucky enough to catch a total eclipse?
Asolar eclipse starts when the Moon just begins to silhouette itself against the
edge of the Sun’s disk.Apartial phase follows, during which more and more of
the Sun is covered by the Moon.About an hour after the eclipse begins, the Sun
becomes completely hidden behind the Moon. In the few minutes immediately
before this period of totality begins, the sky noticeably darkens, some flowers
close up, and chickens may go to roost.As an eerie twilight suddenly descends
during the day, other animals (and people) may get disoriented. During totality,
the sky is dark enough that planets become visible in the sky, and usually the
brighter stars do aswell.

40. AppearanceofaTotalEclipse
As the bright disk of the Sunbecomes entirely hidden behind the Moon, the
Sun’s remarkable corona flashes into view. The corona is the Sun’s outer
atmosphere, consisting of sparse gases that extend for millions of miles in all
directions from the apparent surface of the Sun.Itis ordinarily not visible
because the light of the corona is feeble compared with the light from the
underlying layers of the Sun.Only when the brilliant glare from the Sun’s
visible disk is blotted out by the Moon during a total eclipse is the pearly
white corona visible
The Sun's Corona. The corona (thinouter
atmosphere) ofthe Sunis visible during a total
solar eclipse
The total phase of the eclipse ends, as abruptly as it began, when the Moon
begins to uncover the Sun.Gradually, the partial phases of the eclipse repeat
themselves, in reverse order, until the Moon has completely uncovered the
Sun. We should make one important safety point here: while the few minutes
of the total eclipse are safe to look at, if any part of the Sunis uncovered, you
must protect your eyes with safe eclipse glasses2 or by projecting an image of
the Sun

41. Additional Information
Feature of SolarEclipses
The totally eclipsed Sunis a spectacular sight. With the Moon covering the bright surface of the Sun,called
the photosphere, you can see the Sun'sfaint outer atmosphere, callel the corona, glowing with a pale
white light faint enough that you can safely look at it directly. The corona is made of hot, low density gas
that is given a wispy appearance by the solar magis field. Also visible just above the photosphere a thin
layer of bright gas called the chromosphere. The chromosphere is often marked by eruptions on the solar
surface calledprominences.

43. Video Presentation
Solar Eclipse

44. Eclipses of theMoon
Alunar eclipse occurs when the Moon enters the shadow of Earth. The geometry of a lunar eclipse is shown in this Figure.
Earth’s dark shadow is about 1.4 million kilometers long, so at the Moon’s distance (an average of 384,000 kilometers), it
could cover about four full moons. Unlike a solar eclipse, which is visible only in certain local areas on Earth, a lunar
eclipse is visible to everyone who can see the Moon. Because a lunar eclipse can be seen (weather permitting) from the
entire night side of Earth, lunar eclipses are observed far more frequently from a given place on Earth than are solar
eclipses.
Geometry of a Lunar Eclipse. The Moon is shown moving through the different parts of Earth’s
shadow during a total lunar eclipse. Note that the distance the Moon moves in its orbit during the
eclipse has been exaggerated here for clarity.

45. Eclipses of theMoon
An eclipse of the Moon is total only if the Moon’s path carries it though Earth’s umbra. If the Moon does not enter the
umbra completely, we have a partial eclipse of the Moon. Butbecause Earthis larger than the Moon, its umbra is larger,
so that lunar eclipses last longer than solar eclipses.
A lunar eclipse can take place only when the Sun,Earth,and Moon are in a line. The Moon is opposite the Sun,which
means the Moon will be in full phase before the eclipse, making the darkening even more dramatic. About 20 minutes
before the Moon reaches the dark shadow, it dims somewhat as Earthpartly blocks the sunlight. As the Moon begins to
dip into the shadow, the curved shape of Earth’s shadow upon it soon becomes apparent.
Even when totally eclipsed, the Moon is still faintly visible, usually appearing a dull coppery red. The illumination on the
eclipsed Moon is sunlight that has been bent into Earth’s shadow by passing through Earth’s atmosphere.

46. When the Moon travels tothe
Penumbra, we see a
Penumbral Lunar Eclipse
where the Moon is faintly
visible to us.
When the part ofthe Moon is
in the Penumbra and a part
of it is in Umbra, we see a
Partial Lunar Eclipse.
When the Moon travels tothe
Umbra, we seea Total Lunar
Eclipse.

47. Eclipses of theMoon
After totality, the Moon moves out of the shadow and the sequence of events is reversed. The total duration of the
eclipse depends on how closely the Moon’s path approaches the axis of the shadow. For an eclipse where the Moon goes
through the center of Earth’s shadow, each partial phase consumes at least 1hour, and totality can last as long as 1hour
and 40 minutes.
Eclipses of the Moon are much more “democratic” than solar eclipses. Since the full moon is visible on the entire night
side of Earth,the lunar eclipse is visible for all those who live in that hemisphere. (Recall that a total eclipse of the Sunis
visible only in a narrow path where the shadow of the umbra falls.) Total eclipses of the Moon occur, on average, about
once every two or three years. Inaddition, since the lunar eclipse happens to a full moon, and a full moon is not
dangerous to look at, everyone can look at the Moon during all the parts of the eclipse without worrying about safety.

48. Video Presentation
Lunar Eclipse

49. Observing anEclipse
No matter how thrilling solar eclipse in, you must be cautious when viewing it. During the
partial phase, part of the brilliant photosphere remains visible, so it is hazardous to look at the
eclipse without protection. Dense filters and exposed film do not necessarily provide protection
because some filters do not block the invisible infrared (heat) radiation that can burn the retina
of your eyes. Dangers like these have led officials to warn the public now to look at solar
eclipses at all and have even frightened some people is locking themselves and their children in
windowless rooms. It is a Common Misconception that sun light is somehow more dangerous
during an eclipse. In fact, it always dangerous to look at the Sun. The danger posed by an eclipse
is that people are tempted to ignore common sense and look at the Sun directly, which can burn
their eyes even when the Sun is almost totally eclipsed.

50. Observing anEclipse
Asafe way to view the partul phases of a solar
eclipse.
The safest and simplest way to observe the partial phases of a
solar eclipse is to use pinhole projection. Poke a small pinhole in a
sheet of cardboard. Hold the sheet with the hole in sunlight and
allow light to pass through the hole and onto a second sheet of
cardboard.
On a day when there is no eclipse, the result is a small, round
spot of light that is an image of the Sun. During the partial phases of
a solar eclipse, the image will show the dark silhouette of the Moon
obscuring part of the Sun.
Pinhole images of the partially eclipsed Sun can also be seen
in the shadows of trees as sunlight peeks through the tiny openings
between the leaves andbranches.
This can produce an eerie effect just before totality as the
remaining sliver of Sun produces thin crescents of light on the
ground under trees. Once totality begins, it is safe to look directly.
The totally eclipsed Sunis fainter than a fullmoon.

51. Condition for anEclipse
You can predict eclipses by thinking about the motion of the Sun and Moon in the
sky. Imagine that you can look up into the sky from your home on Earth and see the Sun
appearing to move along the ecliptic and the Moon moving along its orbit. Because the
orbit of the Moon is sipped slightly more than 5 degrees the plane of Earth's orbit, you the
Moon follow path tipped by the same angle to the ecliptic. Each month, the Moon crosses
the ecliptic at two points called nodes. It crosses at one node going southward, and about
two weeks later, it crosses the other node going northward.
Eclipsis can occur only when, viewed from Earth, the Sun is near of the nodes of the Moon's
orbit. Only then can the new moon cross in front of the Sun and produce a solar eclipse, and only
then can the full moon enter Earth's shadow and be eclipsed. Most new moons pass too far north or
too far south of the ecliptic to cause an eclipse. (Note that this requirement for eclipses is the reason
the Sun's apparent path through the sky called the ecliptic) Also, when the Sun is near one node,
Earth's shadow points near the other node, and a lunar eclipse is possible. A lunar eclipse doesn't
happen at every full moon because most full moons pass too far north or too far south of the
ecliptic and miss the umbra of Earth's shadow. Some months you might see a partial lunar eclipse .

52. Condition for anEclipse
Thus, these are two conditions for an eclipse: The Sun must be near one of the two nodes of the
Moon's orbit, and the Moon must pass near either the same node (solar eclipse) or the other node
(lunar eclipse). This means, of course, that solar eclipses can occur only when the Moon is new, and
lunar eclipses can occur only when the Moon is full.
Now you can understand the ancient secret of predicting eclipses. An eclipse can occur only in
a period called an eclipse season, during which the Sun is close to a node in the Moon's orbit. For solar
eclipses, an eclipse season is about 32 days long. Any new moon during this period will produce a
solar eclipse. For lunar eclipses, the eclipse season is a bit shorter, about 22 days. Any full moon in this
period will encounter Earth,shadow and be eclipsed.
This makes eclipse prediction easy. All you have to do is keep track of where the Moon crosses
the ecliptic (where the nodes of its orbit are). Then, when the Sun approaches either of the nodes you
can warn everyone that eclipses are possible. This system work fairly well, and astronomers in early
civilizations such as the Maya may have used such a system. You could have been a very successful
Mayan astronomer with what you know abour eclipse seasons, but you can do even better if you
change your point ofview.

53. Change your point of view and imagine that you are looking at the orbits of Earth and the Moon from
point far away in space. Recall that the Moon's orbit is tipped at an angle to Earth's orbit The shadows of Earth
and Moon are long and thin. That is why it is so easy for them to miss their mark at new moon or full moon and
usually fail to produce an eclipse. As Earth orbits the Sun, the Moon's orbit remains approximately fixed in
orientation. The nodes of the Moon's orbit are the points where it passes through the plane of Earth's orbit; an
eclipse season occurs each time the line connecting these nodes, the line of nodes, points directly toward the Sun,
allowing the shadows of Earth and Moon then to hit their marks.
Look at figure and notice that the line of nodes does not point at the Sun in the example at lower left, and no
eclipses are possible at that time of the year; the shadow miss. At lower right, during an eclipse season, the line of
nodes points toward the Sun,and the shadows produce eclipses.
The View FromSpace

54. If you watched for years from your point of view in space. you would see the orbit of the Moon precess
like a hubcap spinning on the ground. This precession is caused mostly by the gravitational influence of the Sun,
and it makes the line of nodes seem to rotate around the sky, as viewed from Earth, once every 18.6 years. As a
result, the nodes slip westward along the ecliptic at a rate of 19.4 degrees per year. Consequently, the Sun does
not need a full year to go from a node all the way around the ecliptic and appear back at that same node. Because
the node is moving westward to meet the Sun, the Sun will cross the node after only 346.6 days (an eclipse year).
This means that seasons begin about 19 days earlier every year. If you see an eclipse in late December one year,
you can see eclipses in early December the next year, and so on.
Eclipses follow a pattern, and if you were an astronomer in an carly civilization who understood the
pattern, you could predict eclipses without ever knowing what the Moon is or how an orbit works. Once you have
observed a few eclipses from a given location, you know when the eclipse seasons are occurring, and you can
predict next year's eclipse seasons by subtracting 19 days. New moons and full moons near those dates are
candidates for eclipses.
The View FromSpace

55. Additional Information
The orbit of the Moon is slightly elliptical, and its distance from Earth
varies. When it is at apogee, its farthest point from Earth, the Moon's
angular diameter is 5.5 percent smaller than average, and when it is at
perigee its closest point to Earth angular diameter is 5.5 percent larger
than average

56. Additional Information
What causes tides?
High and low tides are caused by the moon. The moon's gravitational
pull generates something called the tidal force. The tidal force causes
Earth—and its water—to bulge out on the side closest to the moon and the
side farthest from the moon. These bulges of water are high tides.

57. Additional Information
Isthere lunar and solar eclipse in other planet?
You might have heard that the Earth is the only planet in our solar system that experiences
eclipses. That is not true. Granted, our eclipses are special, but hypothetical observers on other
planets also could experience partial and total solar eclipses.
All four giant planets (Jupiter, Saturn, Uranus and Neptune) can experience eclipses, since they
all have substantial moons and the Sun appears small from them. Eclipses are most common on
Jupiter, because its moons orbit in the same plane with the Sun.
In addition, Mercury and Venus cannot have eclipses because they have no moons.