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3-3 (Earth, Sun and Moon)
EQ: How do the Earth, Sun and Moon affect each other?
- The movement of the Earth and moon in their orbits
affect the appearance of moon by blocking different amount of light from the
1) What are the phases of the moon?
- The revolution of the moon around the earth causes it
to appear to change shape
- The moon goes through all phases in 29.5 days (its
period of revolution)
- The moon does not have light, it just reflects the
- When the moon comes between the earth and the sun, we
are in the new moon phase (we see total darkness)
- Earthshine is reflected sunlight on the moon by the
- As the moon travels from the new moon (day 1 to about
day 14) the amount of the moon we see grows larger (it is waxing)
- From about day 15 in the orbit (the Full Moon) we
begin to see less and less of the moon (it is waning)
Poem to help you remember waxing and waning:
As we travel
with more light, the waxing moon is on the right.
When the light
gets less and less, the waning moon is on the left.
2) What is an Eclipse?
- When the Earth and moon revolve around the sun they
sometimes block out the sunlight and cast a shadow on the other body.
- The shadow causes an eclipse
- Two types, depend on which body is blocked (in shadow)
- Solar Eclipse- When the moon blocks the
sunlight from the earth (Earth is in the moonís shadow)
- During a solar eclipse- never look at the sun!
- Lunar Eclipse- When the Earth blocks the
sunlight from the moon (Moon is in Earthís shadow)
- The shadows have two parts:
- Umbra- The small, dark inner shadow
- Penumbra- The larger, lighter outer
3) What are tides and how are they caused?
- Tides are the rise and fall of the oceans on the earth
- They are caused by the gravitational pull of the moon
on the Earth
- As the Earth rotates (every 24 hours) the side of the
Earth that faces the moon bulges. This causes a High tide on both
the side of Earth that faces the moon and on the side of Earth
that faces away from the moon
- Low tides occur on both sides that do not bulge
- At any given shore on Earth there are always 2 high
tides and 2 low tides every 24 hours.
- Spring tides: highest high tides Ė When
the Earth, Sun and moon line up in their orbits the sunís gravitational pull
adds to the moonís and the tides are much higher (during the Full and New
- Neap tides: lowest high tides-During the
1st quarter and last quarter the Sun and moon are at right angles
so the affect of their gravity works against each other causing the lowest,
high tides to occur.
- At the moonís perigee we will experience the highest
high tides and low tides.