Download Lesson 5-3

Lesson 5-3
What Holds the
Moon and Planets in
Place?
I.
How Planets Move Through Space
A.
The sun is slightly away from the
center of the solar system
B.
All planets orbit the sun
1.
Orbit – the path that a body
follows as it revolves around
another body
2. Planets orbit in an elliptical
pattern (shaped like a
flattened circle)
3. Because of elliptical orbits,
each planet is closer to the sun
at certain times during the
orbit than others
4.
Orbits are caused when there
is a balance between inertia
and gravity.
a. The 1st law of motion
(Inertia): An object will
continue to move in a
straight line until an
outside force acts on it.
b.
Gravity: A force that
pulls everything toward
the center.
c.
d.
Gravity and Inertia cause
the planets to “fall”
constantly in a curved
path around the sun
distance from a planet to
the sun or from the moon
to Earth never changes
II. The Moon
A.
The moon rotates as it orbits the
Earth
1.
A full rotation occurs
every 29 ½ days
2. Same side of the moon
always faces Earth
B.
The moon is bright at night because
it reflects the sun’s light
C.
Phases of the moon – Because
the moon revolves around the
earth we see it differently
every night
1.
crescent – less than half
2. gibbous – more than half
3. waxing – getting bigger
4. waning – getting smaller
D.
Eight Phases
1. New Moon
2. Waxing Crescent
3. First Qtr
4. Waxing Gibbous
5. Full Moon
6. Waning Gibbous
7. Last Qtr
8. Waning Crescent