Download Earth, Moon, and Sun

Unit 8 Study Guide Notes
Earth moves through space in two
ways: revolution and rotation.
Rotation

It takes 24 hours for Earth to rotate one time on its
axis. This 24 hour period is also called a day.

The earth rotates west to east. This make the sun
appear to rise in the east and set in the west.

http://www.learner.org/jnorth/images/graphics/mclass
/jr/Day2/Day_Sol_S21_RevolvingEarth.gif

https://www.youtube.com/watch?v=jtJkHlKBE1Q&fea
ture=youtu.be
Revolution
It takes 365 ¼ days or
one year for Earth to
revolve around the sun.
This is why stars and
constellations appear in
different places
throughout the year.
The path an object takes
while it revolves is called its orbit.

https://www.youtube.com/embed/R2lP146KA5A?autopl
ay=1&enablejsapi=1&wmode=transparent
The constellations seem to change
location in the sky throughout the
year. What’s really moving?
Revolution

Because revolution is not exactly 365
days, we have to add one day to the
calendar every four years. This is
known as leap year.
1 orbit= 365 ¼ days
¼ + ¼ + ¼ + ¼ = 1 added day
Gravity and Inertia
How do the Earth, moon, and other
planets stay in orbit? gravity and inertia
a. Gravity is a force where two objects
are attracted to each other.
b. Inertia is the resistance of an object to
change its state of motion.
c. Gravity pulls an object toward another
object, but inertia pulls it away.
Gravity and Inertia

http://studyjams.scholastic.com/studyja
ms/jams/science/solar-system/sgravityand-inertia.htm
Ticket Out The Door
1. Define rotation.
2. Define revolution.
3. Which motion makes the sun appear to
rise in the east and set in the west each
day?
4. Which motion makes the constellations
in the sky appear to move throughout the
year?
5. What force keeps the earth from
crashing into the sun?
Answers:
1. the spin of an object on its axis
2. an object makes one complete circle
around another
3. rotation
4. revolution
5. inertia
Seasons
The Earth is tilted at
23.5 degrees on its axis,
and this is why we have
seasons. As Earth
Revolves around the
sun, different hemispheres
will be receiving more or
less direct sunlight based
on whether the pole is tilted
toward or away from the sun.

Seasons
Whatever season is
occurring in the
Northern hemisphere,
the opposite season
will be occurring in the
southern hemisphere.

An Australian Christmas card

http://www.youtube.com/watch?v=Pgq0LTh
W7QA
Seasons

Yardstick practice
Solstices

Solstices are the two days of the year on
which the sun reaches its greatest
distance north or south of the equator.
The days are longer around the
summer solstice (around June 21-22 in
the northern hemisphere) and shorter
around the winter solstice (around
December 21-22 in the northern
hemisphere).
Summer Solstice at the North Pole!

http://www.youtube.com/watch?v=ZZcaf
g-meJA
Equinoxes


The equinox is either of the two days or
periods each year when the sun crosses the
equator and day and night are of equal length
of twelve hours. During an equinox, neither
hemisphere is tilted toward or away from the
sun. The spring or vernal equinox happens
around March 20-22, and the autumnal or fall
equinox occurs around September 22-23 in
the northern hemisphere (and vice-versa in the
southern hemisphere).
http://esminfo.prenhall.com/science/geoanimat
ions/animations/01_EarthSun_E2.html
Moon Motion
a. It takes about 28 – 29 days for the moon
to revolve around Earth.
b. It takes about 28 – 29 days for the moon
to rotate on its axis.
c. Since the revolution and rotation take the
same amount of time, we always see the
same side of the moon from Earth.
Moon Phases

The phase of the moon you see
depends on how much of the sunlit side
of the moon that faces Earth. As the
moon revolves around the Earth, the
amount of light that we can see
changes.
Moon Phases
https://www.youtube.com/watch?v=nXseT
WTZlks
http://www.sumanasinc.com/webcontent/a
nimations/content/moonphase.html
Moon Phases Video
You try!!!
1. Which moon is a waxing gibbous?
2.Which moon is a waxing crescent?
3. Which moon is a waning gibbous?
4. Which moon is a waning
crescent?
5. Which moon is pictured?
a. Full moon
b. First quarter moon
c. New moon
d. Third quarter moon
7.Which moon is pictured?
a. Full moon
b. First quarter moon
c. New moon
d. Third quarter moon
Solar Eclipses
What is a solar eclipse?
 A solar eclipse happens when the
moon comes between the Earth and
sun, blocking the sun’s rays from the
Earth. (The Earth is passing through the
moon’s shadow. In other words, a
shadow is covering the sun.)
 A solar eclipse can only happen during a
new moon.
 Observe solar eclipses.
Solar Eclipses
A total eclipse is when the sun is
completely darkened. The moon is 400
times smaller than the Sun, but the
moon is also 400 times closer to Earth,
so from Earth’s point of view, the entire
sun is blocked.
 The moon’s shadow only covers a small
area on Earth’s surface; therefore, only
a small section of Earth will be able to
observe and experience the eclipse.

Solar Eclipse Animation
A picture of a 1999 solar eclipse
taken from a satellite in space.
Solar Eclipse Video

https://www.youtube.com/watch?v=_201
ttTSG30
Lunar Eclipses
What is a lunar eclipse?
 A lunar eclipse occurs when the Earth
blocks the rays of the sun from the
moon. (The moon passes through the
Earth’s shadow. In other words, a
shadow is covering the moon.)
 A lunar eclipse can only happen during a
full moon.
 A total eclipse happens when the moon
is completely blocked.
The moon is in Earth’s shadow.
Lunar Eclipse from Earth
Lunar Eclipse Video

https://www.youtube.com/watch?v=49O
2MsT1txU
Why don’t eclipses happen every month?

Most of the time the distance of the shadow
is too short to reach the earth or the moon.
Also…

The orbit of the moon is at a 5 degree
angle to the orbit of the earth.
Can other planets have eclipses?
Yes! A picture of Jupiter and its moon Lo taken
by Hubble. The black spot is Lo's shadow.
Spring Tide

When the Earth, moon, and sun are in a
straight line during new and full moons,
a spring tide occurs. The tidal range is
greatest. (High tide is higher than
normal, and low tide is lower than
normal. You will see the greatest
differences between high and low tides
during a spring tide because the sun
and moon’s gravity are working
together.)
Neap Tide

When the Earth, moon, and sun are
forming a right angle during the 1st
quarter and 3rd quarter moons, a neap
tide occurs. The tidal range is lowest.
(There isn’t much difference because
the high tide is lower than normal and
low tide is higher than normal).