the sun, earth, & moonri2.missouri.edu/sites/default/files/presentation-4_2.pdf · the moon is:...
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THE SUN, EARTH, & MOONPhases of the Moon
Something to Think About!
■ Rotation:
– When an object rotates, it spins on its axis
■ The Earth makes one complete rotation on its axis every 24 hours
■ The Moon makes one complete rotation in approximately 28 days
■ Revolution:
– When an object Revolves, it moves around another object
■ The Earth revolves around the Sun
■ The Moon revolves around the Earth
The Sun, Earth, and Moon
■ The Sun is the center of the solar system
■ The Earth rotates on its axis every 24 hours
– Cause of day and night on Earth
■ The Earth has one moon
– The moon makes one complete revolution around the Earth every
28 days
All About The Moon
■ The Moon is:
– Earth’s only natural satellite
– Approximately 384,400 km [238,855 miles] away from the Earth
■ Is the orbit of the Moon around the Earth perfectly circular?
– No, the orbit of the moon is not a perfect circle.
■ When the moon is at the closest point [perigee] the moon is 225,804 miles away
from the earth
■ When the moon is at the most distant point [apogee] the moon is 251,968 miles
away from Earth
Man on the Moon
July 30, 1971
Apollo 15 astronaut Jim
Irwin on the Moon with the
first Lunar Roving Vehicle.
Jim Irwin was the 8th man
to walk on the Moon
Moon Light
■ The Moon is not a star and does not give off light
– The Moon reflects light from the Sun
■ The Moon is rotating on its axis and revolving around the Earth
– The position of the Moon changes during the 29 and ½ day lunar
cycle
The Lunar Cycle
■ As the Moon revolves around
the Earth:
– The shape of the Moon
appears to change
■ Do you think that the shape of
the moon actually changes?
– Study the images of the
lunar cycle before you
answer
More About the Lunar Cycle
■ Only the side of the moon facing the
sun can reflect sunlight.
■ During much of the lunar cycle we
can only see a portion of the sunlit
moon
■ What do you think we see during a
‘new moon’?
■ What do we see when the moon is a
crescent?
The outside images are what
we see when we look up at
the moon from Earth
The portion of the moon
facing the sun reflects
sunlight
Views of the Moon from Earth
■ Green lines represent
portions of the Moon we
cannot see from Earth
■ White areas of the Moon
are what we see from
the Earth
A Waxing Moon
■ When the Moon is said to be ‘Waxing’
– The sunlit part of the Moon at any time before a full Moon
– The sunlit part of the Moon we see is getting larger
A Waning Moon
■ When the Moon is said to be ‘Waning’
– The sunlit part of the Moon at any time after a full Moon
– The sunlit part of the Moon we see is getting smaller
The New Moon
■ During a new moon, we do
not see the moon in the sky
– The dark side of the
moon is facing the
Earth
– The other side of the
moon is very bright
and facing the sun
■ Can you find the new moon
in the picture to the right?
The Waxing Crescent Moon
■ When we see the ‘waxing
crescent moon’ a thin sliver or
crescent of the moon is
visible.
– When we are able to see
a bit more of the moon,
we say the moon is
waxing.
■ Can you find the waxing
crescent moon in the picture
to the right?
The Quarter Moon
■ About one-week after the
new moon, the moon has
completed about one-
quarter of its orbit around
the Earth.
– We are able to see
one-half of the bright
side of the moon.
Actually, that is a
quarter of the moon.
■ Can you find the waxing
quarter moon in the image
on the right?
The Waxing Gibbous Moon
■ As the moon continues to orbit the Earth, we are able to see more of the bright portion of the moon.
– The gibbous moon is nearly a full moon
– We call it a waxing moon because we can see more of the moon from Earth.
■ Can you find the waxing gibbous moon in the image on the right?
The Full Moon
■ When the moon is full, we
are able to see the half of
the moon illuminated by
the sun.
– The Sun, Earth and
Moon are nearly in a
straight line.
■ What other time during the
moon’s orbit are the Sun,
Earth, and Moon nearly in a
straight line?
The Waning Gibbous Moon
■ The waning gibbous moon
is nearly a full moon but
we are seeing less of the
moon.
– We say the moon is
waning and we call the
moon a gibbous moon
because it is nearly full
■ Can you find the waning
gibbous moon in the image
to the right?
The Last Quarter
■ The portion of the moon
lit by the sun is growing
smaller.
– The left half of the
moon is illuminated
by the sun
■ Can you find the last
quarter of the moon in
the image on the right?
The Waning Crescent Moon
■ As the moon appears to be smaller and smaller in the sky, it is called the waning crescent.
– The waning crescent moon will continue to appear smaller and smaller with each day.
■ Can you find the waning crescent moon in the image on the right?
The Moon from the Earth
Something to Think About!
■ How is the Waxing Crescent Moon different from the Waning Crescent
Moon?
■ If you looked into the night sky during the New Moon, would you
expect the stars to be more or less visible in the night sky?
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