Rotation vs. Revolution
Throughout a 24 hour period, Earth will make one rotation
on its axis.
 One rotation= 24 hours= 1 day/night
The fact that moon rotates on its axis in the same amount
of time that it makes one rotation around the sun is why
we only see one side of the moon!
Seasons: The Earth has seasons because its axis is tilted.
As the Earth is rotating, it appears as if the Sun is moving
across the sky (apparent movement).
 East to west- the Sun is stationary, but the Earth is
turning – so the sun appears to rise in the east & set in
the west.
 Earth’s rotation causes Day and Night on our planet.
Everyday examples of rotation:
1. A basketball spinning on your finger
2. Turning on your toes 3. Spinning in a chair
The rotation of the Earth also causes shadows to change.
Shadows are longest in the early morning and at dusk (just
before sunset).
Shadows are shortest at noon 12:00pm because the Sun is
directly overhead.
The Earth takes 1 year (approximately 365 days) to make a
revolution around the Sun.
 1 revolution= 1 orbit around the Sun
 Revolution plus the tilt of the Earth causes the seasons
 The moon is considered a natural satellite of the Earth
since it revolves around the Earth.
Everyday examples of revolution:
1. Walking around a table. 2. Running around a track
The Earth rotates on its axis as it revolves around the sun,
but its axis always points the same direction.
The tilt of the axis causes certain parts of the Earth to be
further away from the sun than others. Ex: When the
Northern Hemisphere is tilted toward the sun the Southern
Hemisphere is tilted away from the sun.
The areas tilted toward the sun experience their summer
season.
The areas tilted away from the sun experience their winter
season.
During Earth’s orbit around the sun, there are also times
when the sun shines equally on both the North and South
Hemispheres. This occurs in spring and fall times.
If the Earth weren’t tilted on its axis, each part of the Earth
would always receive the same amount of sunlight and
therefore their weather would remain the same throughout
the year!
Earth vs. Moon
Earth
Sun Facts
75% water
Moon
Water in the form of ice only
– located in craters.
 The sun is an average sized star in our galaxy –
The Milky Way Galaxy
Rotates once every 24 hours
Rotates once every 28 days
 The sun is one of trillions of stars in space.
Revolves around the Sun=
365 ¼ days
Revolves around the Earth=
28 days
 93,000,000 miles away from Earth
Has mountains, craters,
Has mountains, craters,
canyons, rocks, plains, rivers, canyons, plains, maria, and
oceans, etc.
rock
 The sun is the only star in our solar system.
 The sun is a ball of hot burning gases, mainly
Hydrogen and Helium.
 The sun does rotate on its axis.
Made up of 4 layers- inner
core, outer core, mantle,
and crust
Made up of rock
Supports life
No signs of life
Has an atmosphere (78%
nitrogen, 21% oxygen,
0.9% argon, and 0.03%
carbon dioxide)
No atmosphere
 The sun does have an atmosphere (photosphere,
chromosphere, and corona are the outer layers)
No seasons or weather
 Sunspots that appear on the chromosphere are
darker, cooler areas on the sun.
 The sun diameter is about 110 times the diameter
of the Earth.
 In the Corona (cloud of plasma on the outer
surface of the sun) you can find:
Has seasons and weather
Gravitational pull – 9.8 m/s2
About 1/6 the Gravitational
pull of the Earth
Diameter 12756 km
Diameter is about ¼ the size
of the Earth
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Sunspots- dark, cooler areas on the surface
Prominence- arching storms
Solar flares – explosions on the sun
Solar wind – particles that slip through the magnetic field
of the sun and go into space.
Really, Really, Really Important stuff about the Sun!
Can you name the planets in order?
 The sun is the center of our solar system
Remember this!
 Source of energy for all cycles
1. Light Energy
 Needed for photosynthesis, nitrogen cycle,
and carbon dioxide cycle
 Without it= no plants, no oxygen, no life
2. Heat Energy
 Needed for the water cycle
 Without it= no precipitation, everything would
be too cold and freeze
3. Solar Energy
 Needed for all cycles, for heat, for electricity,
etc.
Gravity
Force that holds planets in orbit
 The Sun’s gravitational pull keeps the planets on their
paths. The Sun’s gravity is about 28 times that of the
Earth.
 Inertia keeps the planets moving.
The Earth’s gravity keeps objects on the Earth from floating
away and pulls them toward the ground, but it also keeps the
Moon in orbit around the Earth.
The pull between the Moon and Earth causes tides.
**Gravity on the Moon is 1/6 the gravity on Earth.
 Steve weighs 60 pounds on Earth. He only weighs 10
pounds on the Moon.
 Steve’s mass stays the same.
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Sun
My
Very
Energetic
Mother
Just
 Served
 Us
 Nachos
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
 Pluto is considered a dwarf planet
now due to its small size.
 It is smaller than our moon!
Moon Phases
Why does the Moon keep changing its shape every
night? Unlike the Sun, the Moon does not produce
its own light. The light we see from the Moon is
reflected from the Sun’s light.
The Sun only shines on one side of the Moon at a
time. As the Moon orbits the Earth, we can see
different parts of the light side, depending on the
locations of the Sun, Earth, and Moon. The changes
we see in the Moon are called moon phases.
When the Sun and Moon are on opposite sides of
Earth, we can see the full moon, because we see the
whole sunlit side. When the Moon is directly in
between Earth and the Sun, we cannot see the Moon
at all; it is a new moon. It takes two weeks for the
Moon to travel halfway around the Earth in its orbit,
from full moon to new moon. After the full moon the
moon is waning as it grows smaller; this is a
crescent moon. After the new moon, it is waxing as
it grows bigger; this is a gibbous moon.
Complete the picture on the right by coloring in the shadowed portions
of the moon at each phase and labeling the phases. Start the new
moon at the circle directly between the Earth and the Sun and go
counter clockwise.
Tides
Tides are the rising and falling of the ocean as a result of
the gravitational pull of the moon.
There are two high tides at a specific location every 24.5
hours. There is a high tide on the side of the Earth facing
the moon due to the moon’s gravity and on the side of
the Earth directly opposite from the moon due to the
inertia of the ocean waters.
Approximately twice a month the Earth has a spring tide
and a neap tide.
Theories of the Universe
Geocentric model of the universe was
established by ancient Greek philosophers and
astronomers such as Ptolemy and Aristotle. In
this model the Earth is the center of the
universe and all the planets (and the moon)
revolve around it.
Heliocentric model of the universe was
developed by Copernicus and proven by
Galileo. It placed the sun in the center of the
universe with the planets orbiting the sun. It
replaced the Geocentric model.
Space Race
The space race between the U.S.A. and the U.S.S.R.
(Russia) began in the late 1950’s. Present John F.
Kennedy challenged the nation to put a man on the
moon by 1970!
Spring tide = an “extra high” high tide that occurs when the
sun, earth, and moon are aligned and the gravitational pull of
the moon and sun work together.
Neap tide = a “lower than normal” high tide that occurs when
the moon is at a right angle to the sun and the gravitational
pulls of the moon and the sun oppose each other.
1st American in space : Alan Shepard
1st American to orbit the Earth: John Glen
1st American to walk on the moon: Neil Armstrong
2nd American to walk on the moon: Buzz Aldrin
Commander of the Apollo 11 mission – moon mission
– Michael Collins