Transcript Chapter 8: Planet Earth and Its Moon

Chapter 8:
Planet Earth and Its Moon
Lesson 1
How Does Earth Move?
VOCABULARY WORDS
A shape that is like a circle stretched
Ellipse
out in opposite directions
Spinning of a planet, moon, or star
Rotation
around its axis
Event in which one object in space
Eclipse gets between the sun and another
object
Movement of one object around
Revolution
another object
Lunar
eclipse
VOCABULARY
Event in which the moon passes through
Earth’s shadow
Path an object follows as it revolves
Orbit around another object
Solar Event in which the moon passes between
eclipse the sun and Earth
The government agency that runs the U.S.
NASA space program
Earth, Sun, and Moon- The sun always illuminates
half of the moon’s surface. As the moon orbits
Earth, the moon’s position in relation to the sun
changes. The positions of Earth, the moon, and
the sun cause the moon’s phases. When the moon
is positioned between the sun and Earth, the
unlighted side of the moon faces Earth. The moon
is not visible because its sunlit side is facing the
sun. This phase is called a new moon. When Earth
is between the sun and moon, the half of the moon
that faces Earth is sunlit and visible. This phase is
called a full moon.
Earth Moves
You cannot feel Earth’s movement, but you are
moving along with Earth. Even though you cannot
sense its motion, you can make observations to
know that it does.
Cause/Effect
Because the Earth is tilting…
1. The sun and stars seem to move across
the sky.
2. I cannot feel Earth’s movement.
Predict- If Earth did not rotate on its axis or move
around the sun, what would be the sun’s position?
The sun would be in one position and stay there.
Apply- How do you know you are moving when
you are riding in a car?
You can see objects move past you outside your
window. You can also feel the car change speed
and direction.
What is the Earth’s axis?
The axis is an imaginary line that runs from
the Earth’s North Pole, through Earth’s
center, and to the South Pole.
What would happen to the length of day
and night if Earth rotated more slowly?
Both day and night would last longer.
Earth’s Rotation
The spinning of a planet, moon or star around
its axis is called its rotation.
Each time Earth makes a full turn around its
axis, it makes one rotation. Earth takes 23
hours and 56 minutes to make one rotation.
When Earth rotates, it turns from west to east.
Earth’s rotation causes day to change into night
and night into day. When a place on Earth is
turned toward the sun, it has daylight.
SHADOWS
When light shines on an object and does
not pass through it, the object cast a shadow. As
Earth rotates, sunlight shines on an object from
different angles.
Shadows are the shortest around
noon because the sun
is directly overhead.
Earth’s Revolution
*An orbit is the path that the moon follows around
the Earth.
*As the Earth rotates, it travels around the sun. The
movement of one object around another is called
revolution.
*Earth takes one year, or about 365 days, to
complete one revolution.
*Gravity is a force that pulls two objects toward
each other. The gravity between Earth and sun
keeps Earth revolving around the sun.
The tilt of Earth’s axis affects how directly the sun
shines on Earth as it travels in its orbit.
March- Neither pole is tilted toward the sun.
June- The Northern Hemisphere is tilted toward the
sun.
September- Neither pole is tilted toward the sun.
December- The Northern Hemisphere is tilted away
from the sun.
SEASONS
As the Earth revolves around the sun, it
is tilted on its axis. Its tilt affects how
places on Earth receive sunlight. When
places tilt toward the sun, it is summer.
When places tilt away from the sun, it
is winter.
Questions/Answers
1. During which seasons are daylight and darkness
closest to being equal? Spring and Fall
2. What causes winter in the Northern Hemisphere?
The North Pole is tilted away from the sun.
3. How is the relationship between the Northern
Hemisphere of Earth and the sun different in June
and December? In June, the Northern Hemisphere of
Earth faces toward the sun. In December, it faces away
from the sun.