Eclipses and Tides

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Eclipses and Tides
Topic 4
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What are tides?

• Tides are cyclic rises and falls of ocean water.
  The cycle takes about 24 hours and 50 minutes
• Ocean tides occur 4 times a day 2 highs and 2
  lows each day

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What causes tides?

• The tides are caused by the gravitational
  attraction between Earth, moon and the sun
  (Although the moon has a stronger gravitational
  pull because its closer)

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Where and when does high tide occur?

• High tide occurs on the sides of the earth that
  are aligned with the moon. It occurs twice a day.

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Where and when does low tide occur?

• Low tide occurs on the sides of the Earth that
  is at a right angle to the places having high
  tides. It also occurs twice a day.

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How long does it take to gofrom one high tide to
the next?

• A complete tide cycle of 2 highs and 2 low tides
  take 24 hours and 50 minutes and the tides switch
  from High to Low to High to Low.
• Therefore, it takes about 12 hours and 25
  minutes to go from one high tide to the next

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What is a spring tide?

• A spring tide is a tide that produces high tides
  that are higher than normal and low tides that
  are lower than normal.
• It occurs when the Sun, moon and Earth are all
  aligned.

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During what phases ofthe moon does a spring
tide occur?

• New and Full Moons

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What is a neap tide?

• A tide that produces tides that are not as high
  or low as normal. (moderate changes)

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During what phases ofthe moon does a neap tide
occur?

• First and Third Quarter

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What is an eclipse?

• When a celestial object partially or completely
  comes into the shadow of another celestial
  object.
• There are two types of shadows
• - An Umbra and a Penumbra
• An Umbra is the darker part of the shadow
• A Penumbra is the lighter part of the shadow

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What is a lunar eclipse

• When the moon moves into the shadow of the Earth.
• Visible by all people having night
• Can last up to 100 minutes
• There are two lunar eclipses per year

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During what phase of themoon does a lunar
eclipse occur?

• A Lunar eclipse can occur during the Full moon
  phase.

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What is a solar eclipse?

• When the moon blocks out the sun by casting a
  shadow on Earth.
• Can last up to 7 1/2 minutes
• Occurs once every 200 years for any given
  location.

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During what phase of themoon does a solar
eclipse occur?

• A solar eclipse can occur during the New Moon
  phase.