Discusses what it is, how it got there, some information about its physical features, and talks about how it effects things here on Earth.

1. Our Favorite
Little
Satellite
It’s pretty, but how
did it get there? The Moon
By Moira Whitehouse PhD http://www.areavoices.com/
photo courtesy of Bob King

2. The currently accepted theory for the
formation of the Moon is called the “Giant
Impact” theory. It states that about 4.5 billion
years ago, just a few
million years after
Earth had formed, a
large body (about
the size of Mars)
smashed into Earth.

3. As a result, a gusher of molten hot material was
ejected into space as a cloud of debris which fell
into an orbit
around Earth.
This debris came
primarily from the
Earth’s mantle.
Due to Earth’s
gravity, most of theNASA
heavier material in this cloud eventually fell
back to Earth, while lighter material remained
in orbit around Earth becoming the Moon.

4. Evidence for this idea is found in the rocks
that NASA astronauts have brought back
many moon rocks. The composition of these
rocks is similar to Earth rocks.
Most of
these rocks
were
formed
between 3.8
and 4.1
billion years

5. Although it looks small up there in the sky, the
moon is a
pretty large
hunk of
rock. The
diameter of
the Moon is
about ¼ the
diameter of
the Earth, but
Wikipedia commons
because it is made from lighter stuff, it is only
1/6 of Earth’s mass.

6. Because the Moon’s mass is less , its gravity is
also less than Earth’s—about one-sixth as
much.
Since weight If this man
depends on weighed
240 lbs on
gravity,
Earth, he
everything on would
the Moon would weigh only
weigh about 40 lbs on
one-sixth as the Moon.
much as it does
on Earth.

7. This boy weighs
60 pounds on
Earth.

8. On the Moon he
would only weigh
10 pounds.

9. Also, everything you lifted would be much
lighter on the Moon that it would be on
Earth. However, its mass (the amount of
matter in it) would not change.

10. Astronaut Alan Shepard struck two golf balls
with a golf club on the Moon, driving them, as
he jokingly put it, "miles and miles and miles."

11. Because it has less gravity, astronauts
made some fantastic jumps on the Moon.

12. Although the Moon’s gravity is less than Earths, its
gravity is strong enough to affect us. Everything is
pulled by the Moon’s gravity, but the only thing
noticeably affected is water in the oceans. The
tides occur because of this gravity’s affect on the
planet. Interestingly,
scientists think that it is
also because of the tidal
effect that the Moon is
slowly drifting further
away from the Earth at
a current rate of 4 cm/yr.

13. Tidal Bulge Animation
http://kingfish.coastal.edu/marine/Animations
/Tides/Tides1.html

14. As interesting as gravity on the Moon is, the
role gravity plays in relationship between the
Sun, Earth and Moon is even more so.
It is gravity that keeps the Earth orbiting
(revolving around) the Sun, the Moon orbiting
Earth’s axis
the Earth.
Moon orbits
the Earth
Earth orbits
the Sun

15. As it orbits the Earth
(once every 29.5 days),
the Moon is also
rotating on its axis,
(once every 29.5 days).
Like the Earth the
Moon rotates on its
axis except much
slower, once a day for
Earth verses about once
a month for the Moon.
NASA

16. Because the Moon makes one revolution in
exactly the time it takes to make one orbit of the
Earth, the same side of the moon always points
toward the Earth. From Earth, therefore, we
see only one, always the same, side of the
Moon. The other side faces away from Earth
and is often called the dark side of the moon.
A more accurate term to describe the side of
the moon we see is the near side and opposite
side as the far side. The near side will always
face toward the Earth, and the far side will always
face away.

17. Also because the Moon is rotating (although very
slowly), each side, at some point, faces the Sun and
at some point, away from the Sun. So the Moon
has a day side and a night side, just like the Earth.
But on the Moon the
days and the nights last
about half a month
each. The parts of the
Moon we can see are
. “day” parts of the
the
near side, the “night”
parts are dark and the
far side is not visible from Earth.

18. To help visualize the idea that we always
see the same side of the moon, imagine
that you are an astronaut who was landed
in the middle of the near side of the Moon
and had to stay there for one month
before you could be picked up.
As the Moon slowly
rotates while orbiting
the Earth, you remain in
the center of the near
http://www.areavoices.com/ graphic courtesy of Bob King
side nearest Earth.

19. Thinking about being on the Moon…
The following should interest future astronauts:
Water on the Moon?
Atmosphere on the Moon?
The Moon’s structure and topography?

20. Scientists are not
sure that there is
water on the moon.
Recent explorations
landed a lunar
Water??? probe near the
Moon’s north pole
looking for evidence
of water. There
apparently was
some evidence of
South pole of Moon water in the form of
ice.

21. The Moon has virtually no atmosphere.
Therefore, there is no weather on the Moon,
no storms, no rain, no wind, no snow, but
Atmosphere???
the temperature can fluxuate wildly.
The temperature on the Moon ranges from
daytime highs of about 130°C = 265°F to
nighttime lows of about -110°C = -170°F

22. The fact that the Moon has little or no
atmosphere affects other things on the Moon.
For example, there is no wind or water caused
weathering, erosion or deposition on the
Moon. Things do not erode.
This footprint would look the same today as it
did 30 years ago.

23. The lack of atmosphere also affects sound as
we know it. For sound to travel, there must be
a medium for the waves to travel through.
On Earth that would usually be air or water.
On the Moon, there is no air, so sound
cannot travel above the surface.
When the Apollo astronauts were out on the
Moon's surface, they could only talk to each
other, and to mission control, by using the
radios in their air filled helmets.

24. When the astronaut in the photo hit the
moon’s surface with this shovel, no
sound was made.

25. Another result of no atmosphere on the Moon:
Even during the day time the sky looks black because
the atmosphere is not there to scatter sunlight.

26. The moon was formed about 4.5 billion of years
ago. Most of the structures we see today, the
maria and the highlands, were formed between
3.0 and 3.9 billion years ago.
Structure???
During that time, the Moon was bombarded by
meteorites, comets and asteroids. Some of
them were very large and created large impact
basins.
The crust of the Moon was cracked in some places
by this bombardment and magma from the interior
flowed out on to the surface filling these impact
basins.

27. Earth was also bombarded by objects
from space. However we see only a few
meteorite craters because most objects
burned up during entry due to friction
with Earth’s atmosphere. The craters
created by objects that did actually hit
the surface have been eroded away by
wind, rain, and other forces.
There are, however, many craters on the Moon
since it has no atmosphere to burn up the
meteorites on entry and since there is no wind
or rain to erode the impact craters away.

28. No volcanoes, no fold or no fault mountains
are found on the Moon.
The Moon does have “moonquakes”.
Almost all moonquakes are smaller than
Earth’s constant grumblings and are not
caused by plate movement.

29. Seeking information on Moonquakes,
Astronaut Buzz Aldrin deploys a
seismometer in the Sea of Tranquility.

30. There are several mountains and mountain
ranges on the Moon.
These mountains are almost always found on
the rims of large craters formed by impacts by
objects in space.
Several lunar mountains are well over 10,000
feet tall.
The Moon does not have jagged mountains,
instead the Moon's mountains are round and
smooth.

31. Moon mountain in foreground, the Sun
and planets in background.
http://www.areavoices.com/ photo courtesy of Bob King

32. The prominent Sculptured Hills were
photographed by astronauts Schmitt and Cerman
on Apollo 17. Although these hills are quite
impressive, the highest mountains on the moon
are 15,000 to 20,000 feet high.

34. The never ending bombardment of the Moon has
continuously fractured and sandblasted the rock
Astronaut Harrison Schmitt collecting rocks
from the Moon during the Apollo XVII mission.
surface creating a layer of loose “soil” made up of
dust and broken rock called the regolith.
The uppermost part of
the regolith is mostly fine,
glassy, slippery dust.
This lunar regolith covers
Regolith
the Moon from a depth of
a few meters on the mare,
to a few tens of meters on
the highlands.

35. What is it like on the Moon?
On a clear night of moon observing, one
can see that there are two types of
topography on the Moon’s surface—the
dark colored regions called the maria and
the light-colored highlands that surround
the maria.

36. Photo
Mare of the
near
side of
the
Moon
Highlands
http://sos.noaa.gov/

37. The flat, dark colored, smooth areas that were
created appeared from Earth like “seas”.
They were named maria (Mare, singular),
which means seas because early
astronomers thought they were
Maria
filled with water.
They are now smooth, flat
plains with little evidence of
their earlier bombardment.
The dark material filling the Maria is
actually dark, solidified lava from http://starchild.gsfc.nasa.gov/
that earlier period of induced Lunar volcanism.

38. After the earlier period of maxiummaria
formation, the surface of the Moon has not
changed very much.
There are some moonquakes which cause
occasional landslides.
The daily heating and cooling of rocks
breaks up the rock but at a very slow rate.
But the main on-going geological activity is
continuing meteoritic impacts but at a much
much much slower rate than in the heavy
bombardment in the early history of the
Moon.

39. Maria on
the near
side of
the
Moon
Wikipedia Commons

40. The highlands are hilly and heavily cratered
and cover about 80% of the total lunar
surface.
Highlands
The far side of the Moon is made up almost
entirely of highlands with many many craters
and very few of the dark smooth basins
called maria.

41. Here we have black and white
photos of both sides of the Moon.

42. The same photos artificially colored, give us a good
idea of surface elevations on the moon.

43. While looking closely
at the Moon, you see
circles of varying
circumferences,
which are the craters.
Most craters have a
circular outline; a
few are more
elliptical shapes.
There may be as many as 200,000 craters, most
of them quite small, on the Moon's surface.

44. A crater consists of
a thin elevated ring
forming its
perimeter.
The surface within the ring is a bit below
the surrounding edge and in the center
there is often a peak.

45. Craters
range in size
from a
diameter of
less than
one mile to
over 100
miles across.

46. Möltke – a small bowl-shaped crater
Sabine and Ritter larger, more flattened craters
Sea of Tranquility
The oldest basins are
more irregularly shaped;
the younger ones a more
circular shape.

47. To open,
select this
one.
http://svs.gsfc.nasa.gov/vis/a000000/a003500/a003582/index.html

48. Phases of the Moon

49. What causes the Moon's phases?
The Moon goes through phases (the view seen
from Earth at various times in the Moon cycle)
because:
1) the Moon is revolving around the Earth,
2) the Moon is reflecting sunlight towards
the Earth.
Half of the Moon is always in sunlight, half if it
is dark: however, we can see only the lit
portion which, depending on it’s position in
the orbit, usually gives us a view of only part
of the Moon.

50. Although it is really a continuous and
gradual change, there are eight
recognized phases that the moon goes
through and they always occur in the
same order.
In this repeating pattern the Sun's light
moves, in our view, from right to left
across the surface of the Moon.

51. The phases of the Moon are:

52. As shown in the diagram, the new moon
occurs when the moon is positioned
between the earth and sun. The entire
illuminated
(lit up) side of
the moon is on
the back part
of the
moon–
the half that
we cannot see.
http://www.wiseg
orilla.com

53. At a full moon, the earth, moon, and sun are
in approximately lined up, just as the new
moon, but this time the moon is on the
opposite side of the
earth. As a result,
the entire sunlit
part of the moon
is facing us. The
shadowed portion
is entirely hidden
from view.
http://www.wise
gorilla.com

54. The first quarter and third quarter moons
(both often called a "half moon"), occur when
the moon is at a 90 degree angle with respect
to the Earth
and Sun. So we are
seeing exactly half
of the Moon
illuminated and
half in shadow.
http://www.wise
gorilla.com

55. Although we
give names to
certain phases,
each night the
change is
actually
gradual.

56. Select Moon Phases in the following URL
for an outstanding animation of the Moon
and its phases.
Select “Moon Phases”
http://www.valdosta.edu/~cbarnbau/astro_de
mos/frameset_moon.html

57. Let’s look at the phases of the moon on a
calendar for November, 2009. Notice that
the change from phase to phase is very
gradual and takes about a month for the
cycle.
http://www.tutiempo.net/en/moon/

58. It takes about one month, 29.5 days,
for the Moon to orbit the Earth.
Which, of course, is also the time
from one new moon to the next.

59. Buddhist Proverb
Three things that cannot long be hidden:
the sun, the moon and the truth.