1. Sun, Moon, and Earth

2. Earth
• Rotation- Earth spinning on its axis
– Axis- imaginary line that passes
through Earth’s center from north to
south poles
– Rotation causes day and night
(clockwise- east to west)
– Takes Earth 24 hours (1 day) to
rotate once on its axis

3. Earth
• Revolution- movement of one object
around another object
– One complete revolution around the
sun= 1 year
– Earth’s path as it revolves around
the sun; orbit which is elliptical
(oval)
– Orbit- the path an object takes
around another during a revolution

4. Earth
• Calendar
– Earth’s orbit around the sun takes
about 365 ¼ days (365.25 days) or
1 year
– Leap year every 4 years we make up
the extra day. February has 29 days
in leap year. (4 x ¼ =1)
– The time between one full moon and
the next is about 29 ¼ days
(12 x 29.25 = 351.0 days)

5. Seasons
o Latitude- Distance north or south
from the equator; measured in
degrees
 Equator gets more solar energy
(radiation)- straight sun rays
 Higher latitudes are colder- angled
sun rays

6. Seasons
• Earth’s tilt is 23.5˚ North or South
making the axis tilt toward the sun part
of the year and away from the sun the
other part; always points toward the
north star
• Seasons are determined by how light
hits Earth

7. Seasons

8. Seasons
• When north is tilted toward the sun,
Northern Hemisphere has summer,
Southern has winter
• When Northern Hemisphere is tilted
away from sun, has winter, Southern
has summer
• Solstice- the two days of the year when
the sun is directly overhead

9. Seasons
• Summer- Northern Hemisphere is tilted
toward the sun; more hours of daylight
– June- Summer solstice, longest day of
the year, June 21, first day of
summer

10. Seasons
• Winter- Northern hemisphere tilted
away from sun, less hours of day light
– December- Winter solstice; shortest
day of the year, December 21, first
day of winter

11. Seasons

12. Seasons
• Equinox- equal day and night, sun
directly above the equator;
• March 21- Vernal equinox, spring
• September 23- Autumnal equinox, fall

13. Moon
• The moon is a satellite of Earth: it
revolves around the Earth
• Moon has almost no atmosphere
• Surface- detailed study of moon rocks
gathered by astronauts
– Craters- cover much of the moon’s surface
– Highlands- mountains
– Maria- once flooded with molten material;
appear as dark, flat areas

14. Moon
• The position of the moon, Earth, and
the sun cause the phases of the moon,
eclipses, and tides.
• The moon’s movement
– Moon’s revolution is about 27.3 days
– Moon’s rotation is about 27.3 days
• The moon’s “year” and “day” take the
same amount of time.
• The “far side” of the moon always
faces away from Earth; you never see
it.

15. Moon
• Gravitational pull- the moon and Earth
both pull on each other
• Moon’s density is about the same density as
Earth’s outer layers
• Formation- Collision Theory- states that
about 4.5 billion years ago a large object
collided with Earth; material from this
collision was thrown into orbit around
Earth, eventually forming the moon.

16. Moon Phases
• Phases: the different shapes of the moon
that we see from Earth
• What causes the phases?
– The moon reflects light from the sun; half
of the moon is always lit, and half is dark.
– The amount of sunlit side of the moon that
faces Earth
– As the moon revolves around Earth, the light
side of the moon rotates around, changing
the amount we see from Earth.

17. Moon Phases
• Full- the entire lit side of the moon is
seen
• Gibbous- over half of the lit side is seen
• Quarter- you can only see half of the lit
side of the moon (1st and 3rd/Last)
• Crescent- less than half of the lit side
is seen; thumbnail shaped
• New- the entire dark side is seen

18. Moon Phases
It takes about 29.5 days from one new
moon to the next : 1 complete cycle
• Waxing- the amount of lit side of the
moon seen is increasing
• Waning- the amount of lit side of the
moon seen is decreasing
• http://sunshine.chpc.utah.edu/labs/moon/lunar_phase3.swf
• http://youtu.be/2aFGNGEcDOk
http://youtu.be/3PycZtfns_U

19. Moon Phases

20. Tides
• Tide- the daily rise and fall of Earth’s
coastlines
• Tidal bulge- the moon’s gravitational pull
on the water at the point closest to the
moon, and on the opposite side creates a
bulge of water; high tide
• Low tide- the points between the high tide
points have low tide.
• There are 4 tides a day; 2 high and 2 low

21. Tides
• Spring tide- at the new and full moons,
the sun and moon are lined up. Their
combined gravitational pull creates the
biggest difference between high and
low tides.
• Neap tide- at the 1st and 3rd quarters
of the moon, the sun and moon pull at
right angles to each other. This makes
the least difference between the high
and low tides.

22. Tides

23. Tides

24. Eclipses
When the moon’s shadow hits Earth or
the Earth’s shadow hits the moon
• Solar Eclipse- the moon passes between
Earth and the sun casting a shadow on
the Earth; a new moon in which the
moon blocks the view of the sun.
• Lunar Eclipse- when the Earth passes
between the sun and the moon

25. Eclipses
Lunar Eclipse
Umbra - darkest part of a shadow
Penumbra- part of the shadow surrounding the
darkest part

26. Eclipses

27. Big Bang Theory
• The theory that the universe began with a
very large explosion, distributing thermal
energy and radiation throughout the
universe; cosmic background radiation;
one of many theories/beliefs.
• Scientists discovered the universe is
expanding; they began to think there had
to be a starting point, where all of the
matter in the universe was contained in a
small space.

28. Earth in the Universe

29. Geocentric
• Astronomy- the study of the moon,
stars, and other objects in space
• Ptolelmy: 140 CE; Greek astronomer
who, based on careful mathematical
calculations, thought that the Earth
was at the center of the universe and
the sun and other planets revolved
around the Earth.

30. Heliocentric
• Copernicus: 1543; Polish astronomer
who came up with the theory that the
sun was at the center of the
universe, and all of the planets
orbited the sun.
• Kepler: 1609; Danish; announced that
the planets orbited the sun in elliptical
orbits.

31. Gravity
• Galileo: 1609; one of the first people to
use a telescope to observe objects in the
sky, especially the moon.
• Discovered craters and mountains on the
Earth’s moon.
• Isaac Newton: 1687; Laws of Gravity
– What goes up must come down
– All objects in the universe attract each
other through gravitational force

32. Sun
• Energy from the sun lights and heats
Earth’s surface
• The only star in our solar system
• Is a yellow Dwarf star
• The corona forms the sun’s outer
atmosphere
• The photosphere is the visible part of the
sun that we see from Earth.
• The core is where the sun’s energy is
produced.

33. Sun

34. Sun
• Sunspots: cooler dark spots that form in
the photosphere when convection activity
slows down. Caused by magnetic fields.
• Solar flares: regions of very high
temperature and brightness. Also caused
by magnetic fields.
– May erupt sending streams of
electrically charged particles into the
solar system