Moon Phases, and Eclipses
• Motions of the Moon– Moon revolves around
the Earth and rotates on its axis.• Takes 27.3 days to
revolve around Earth.• Rotates slowly on its
axis, once every 27.3 days.
– Earth only sees the same side of the moon.• “Far side” always faces
away.
• Phases of the Moon– We see the moon
because it reflects light from the sun.
– The moon’s shape changes during the month causing the phases.
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• Phases of the Moon
– New Moon• The sun lights the side
of the moon facing away from Earth. This side of the moon that faces the Earth is dark.
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• Phases of the Moon
– Waxing Crescent• You see more and
more of the lighted side of the moon.
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• Phases of the Moon
– First Quarter• You see half of the
lighted side of the moon.
• The moon is ¼ of the way through it’s orbit.
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• Phases of the Moon
– Waxing Gibbous• The moon continues
to wax. • The moon is called a
waxing gibbous.
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• Phases of the Moon
– Full Moon• The whole lit side of
the moon can be seen from Earth.
• This is known as a Full Moon.
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• Phases of the Moon
– Waning Gibbous• The Moon now
becomes darker each day. This is known as a waning gibbous
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• Phases of the Moon
– Third Quarter Moon• You can see half of the
moon’s lit side. The moon is ¾ of the way through it’s orbit. This is called a third quarter moon, or last quarter moon.
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• Phases of the Moon
– Waning Crescent• The last phase before
new moon.
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C
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Phases
Cause
Eclipses
• Phases of the Moon– Phases are caused by
changes in the relative positions of the moon, Earth and sun.• As the moon revolves
around the Earth, we see the moon from different angles.
– The phase of the moon depends on how much of the sunlit side of the moon faces Earth.
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• Phases of the Moon– The cycle begins at
new moon.– The amount of light on
the moon will gradually increase (Waxing) to full moon.
– After full moon, the light will gradually decrease (Waning) back to new moon.
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• Phases of the Moon– One lunar
cycle lasts 29.5 days.
Objective: I will be able to describe how the Moon moves and what causes the phases.
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• Eclipses– The moon’s orbit is
slightly tilted.
– As a result, the moon doesn’t always
pass into the Earth’s shadow or the shadow from the moon isn’t cast on the Earth.
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• Eclipses– When the moon’s shadow
hits the Earth or the Earth’s shadow hits the moon, an eclipse occurs.
– An eclipse occurs when an object in space comes between the sun and a third object and casts a shadow on that object.
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• Solar Eclipse– Occurs when the moon is in the new moon
phase and it passes between the Earth and the sun.
– Blocking sunlight from the Earth.– The moon’s shadow hits the Earth.
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• Total Solar Eclipse– Occurs when the
darkest part of the moon’s shadow, “the umbra” hits the Earth.• Sunlight is completely
blocked in any part of this shadow.
• Must be in the shadow of the umbra to see a total solar eclipse.
• Stars, and the corona are visible.
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• Partial Solar Eclipse– Occurs when the less
dark shadow “the penumbra” hits Earth.
– People in the penumbra only see a partial eclipse.
– Part of the sun is still visible.• It is not safe to look
directly at the sun.
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• Lunar Eclipse– Occurs at a full moon when the Earth is
directly between the moon and the sun.– Earth blocks sunlight from reaching the moon.– The moon is in the shadow and looks dark.– Can only occur during a full moon.
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• Total Lunar Eclipse– Occurs when the moon
is in the Earth’s “umbra”• The dark shadow.
– Can be seen anywhere on the dark side of the Earth where the moon is visible.
– More likely to see a lunar eclipse than a solar eclipse.
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• Partial Lunar Eclipse– Occurs if the Earth,
moon and sun are not quite in a line.
– The moon only partially passes into the umbra of the Earth’s shadow.• Edge of shadow appears
blurry.• Last up to 2 or 3 hours.
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