The Moon

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The Moon

• The moon is earths only natural satellite
• The moon orbits/revolves around the earth
• It is believed that the Moon and the Earth were
  formed at the same time from the same nebulae
  that created the planets. The moon being smaller
  was probably captured by the earths gravity.
• The moons rotation is equal to its revolution
  around the earth, therefore we only see one side
  of the moon at all times. The only people who
  have seen the other side (the dark side) have
  been the astronauts.

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• The earth has other objects orbiting around it,
  we call these artificial satellites.
• In 1957, USSR put up the first satellite
  (Sputnik I)
• 14,000 artificial satellites have been launched
  since then.
• USA, Russia, Japan, Canada, India, China,
  Australia, Europe.
• some are communication satellites, military
  satellites, remote sensing satellites, weather
  satellites, GPS satellites etc.

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• The moon has no atmosphere
• The moon is 376, 275 km away from the earth
• The moon has no light of its own, it is all
  reflected light from the sun
• The moon was visited by humans in 1969. Twelve
  men have visited the moon
• The moon has two basic features The flat lands
  called Seas and the uneven land made up of impact
  craters.
• Because the moon is so small its gravity is
  weak. A human would weight 1/6 of his/her weight
  on the moon.

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Phases of the Moon

• The moons orbit takes it around the earth in
  about 30 days. I wonder where the word month came
  from?
• Phases of the moon are the apparent changes in
  shape due to the changing illumination of the
  moon by the Sun, as seen from Earth. Moonlight is
  just reflected sunlight.
• Please refer to the next slide for a wonderful
  diagram. Also on the web page there is an
  excellent animated GIF illustrating the phases of
  the moon.
• A New Moon is when you cannot see the moon at
  all. The night side faces the earth.
• A Full Moon is when you see the entire day
  half of the moon. (Werewolves!)

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• A Waxing moon is when you see more and more of
  the moon each night. What is a Waning moon?
• Check out the CRESCENT moon!
• it takes 29 and half days to go from new moon to
  new moon (this is called a lunar month). It takes
  27 and half days for the moon to go once around
  the earth (this is called a sidereal month)
• It takes two extra days for the moon to go from
  new moon to new moon because as the moon rotates
  around the earth, the earth is revolving around
  the sun, the two extra days is for the moon to
  catch up to this new position.

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• It was the moons position in the sky that
  established one moonth one month
• However, 12 periods of 29.5 days equal 354 days
• Hence, the problem of eleven (11) extra days and
  the awkward attempt to solve it by varying the
  lengths of the months

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Eclipses - Solar and Lunar

• Both the earth and the moon cast long shadows
  into space
• When either the earth or the moon pass through
  these shadows, it is known as an eclipse
• There are two kinds of eclipses

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• SOLAR ECLIPSE
• When the moon passes directly between the sun
  and the earth, the moon blocks outor eclipses
  the sun
• Occurs during the day, in the phase of the new
  moon
• A solar eclipse can be total, if the entire sun
  is eclipsed, or partial, if only a section of the
  sun is hidden from view. If we see the moon
  inside the Sun it is called a Annular Eclipse
• The maximum duration is 7 min and 30 seconds
• It is during this time that we can see the
  Corona of the Sun.

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This is called a Diamond Ring
We can see the Suns Corona
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• LUNAR ECLIPSE
• During the night, in the phase of the full moon,
  the earth may come between the moon and the sun.
  People on earth will see the shadow of the earth
  on the moon, causing a lunar eclipse. In other
  words the moon passes through the earths shadow
  and we get to see it. A lunar eclipse does not
  happen every full moon because the moons orbital
  plane is tilted from that of the earths.
• When the moon is being eclipsed by the earth, it
  is not completely blacked out in the way the sun
  is during a total solar eclipse instead, the moon
  appears as a dull red ball, lit by a small amount
  of sunlight refracted to it through the earths
  atmosphere. It may last up to 2 hours.
• There are two types of shadows created. A
  Penumbra outer shadow/partial eclipse/not
  total black out and an Umbra inner
  shadow/total eclipse/total black out

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The Moon and the tides on Earth

• Tide is the name given to the periodic rise and
  fall of the sea.
• Tides are caused mainly by the gravitational
  pull of the moon and the sun pulling on the
  waters of the earth, thus causing them to bulge.
  The moon has a greater effect on tides because it
  is closer to earth.
• The gravitational pull of the moon causes two
  bulges in the earths oceans. One occurs on the
  side facing the moon and the other on the
  opposite side, this is a compensatory bulge due
  to the earths centre of gravity and its
  rotation. These bulges are called high tide. The
  other two areas on the earth are said to be in
  low tide. The diagram on the next few slides will
  explain.

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• Since the earth makes one complete rotation
  every 24 hours, every place on earth should
  receive two high tides and two low tides. The
  tides are approximately 12.5 hours apart.
• The difference in water level between high and
  low tide is known as the tidal range. On most
  coasts it is commonly 2 - 4 meters. In enclosed
  seas like the Caribbean it is usually less than a
  meter and in the Mediterranean it is almost zero.
  Certain places experience a very great tidal
  range owing to the funnel like nature of the bay.
  The Bay of Fundy in Nova Scotia has a tidal range
  of about 12 - 15 meters.
• When the moon and the sun are aligned with the
  earth the high tides are higher and the low tides
  are lower, these are called Spring Tides.
  Spring tides occur twice a month. When the moon,
  earth and sun form a right angle with each other
  the high tides are a bit lower and the low tides
  are a bit higher. This situation is called a
  Neap Tide.

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• Tides are important for a number of reasons
• They have a great impact on navigation in
  coastal waters and harbours and are a factor to
  be taken into account in the design of harbour
  installations.
• In bays and lagoons, they are partly responsible
  for landforms called tidal or mud flats that can
  occur at spring tides.
• High tides can provide hydroelectric power.
• Problems expensive, engineering difficulties
  environmental concerns (Bay of Fundy)

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