Phases, & Eclipses
Chapter 1: Earth, Moon, & Sun
Motions of the Moon
Why is the “day” on the moon the
same length as a “year” on the
moon?


Rotation : Day :: Revolution : year
Since it takes 27.3 Earth days for
the moon to rotate (day) and 27.3
Earth days for the moon to revolve
(year), the day and a year are the
same length
Checkpoint: How many days does
it take the moon to revolve once
around Earth?


It takes the moon 27.3 Earth days to
revolve around Earth.
It also takes the moon 27.3 Earth
days to rotate
Phases of the Moon
The different shapes of the moon
you see from Earth are called
_____.

phases


The moon goes through its whole
set of phases each time it _____
around Earth, or about once a
_____.
revolves
month
Guide For Reading:What causes
the phases of the moon?




The phases of the moon are caused by the
change of the relative positions of Earth,
the moon, and sun.
Since the moon revolves around Earth we
see it from different angles
The ½ of the moon that faces Earth is not
always the ½ lit up by the sun causing the
moon’s shape to appear to change
The phase of the moon you see depends on
how much of the sunlit side of the moon
faces Earth
What is the length of time
from a new moon to the next
new moon?


29.5 Earth days
Since Earth is revolving it takes an
extra 2.2 Earth days for the sun,
moon and Earth to line up, causing the
next new moon
Checkpoint: Since the moon does
not produce light, how can you
see it?

Light from the sun reflects off the
moon, enabling it to be seen from
Earth.
Eclipses
Figure 6: Interpreting Diagrams
How large is the angle between
Earth’s orbit and the moon’ s orbit?

The angle between
Earth’s orbit and
that of the of the
moon is 5º
When does an eclipse occur?

In a rare occasion when the moon or
Earth becomes directly between the
sun and the other and cast a shadow
on that object
The two types of eclipses are
______ & ______.
lunar
 solar

Solar Eclipses
Solar Eclipse
A solar eclipse occurs when the moon
comes directly between the sun and
Earth
 The moon blocks Earth from sunlight
and cast a shadow
 Earth’s sky becomes darker and you
can only see the corona of the sun

At what phase of the moon
could a solar eclipse occur?

A new moon when the moon becomes
directly between the sun and Earth
The darkest part of the moon’s
shadow is called the
_________.

Umbra
Why are the people in the umbra
the only ones that experience a
total solar eclipse?
The umbra is the darkest part of the
moon’s shadow
 People who are in the umbra are in
the darkest part of the shadow
where the moon is almost completely
blocking sunlight from reaching
Earth, except for the sun’s corona

Penumbra

The larger less dark shadow cast by
the moon during a solar eclipse and by
Earth during a lunar eclipse
Lunar Eclipses
What is a lunar eclipse?
A lunar eclipse occurs when Earth
comes directly between the sun and
moon
 Earth blocks the moon from sunlight
and cast a shadow
 The moon turns a red/orange color

Figure 8: Interpreting Diagrams:
What is the difference between
Earth’s umbra and penumbra?

The umbra is in
the area of total
darkness, the
penumbra is the
area of partial
darkness
Checkpoint: Why do lunar eclipses
occur only at full moon?

Earth must come between the sun and
the moon during a lunar eclipse; this
only happens during the full moon
phase.
Guide For Reading: What
causes solar and lunar
eclipses?
When the moon’s shadow hits Earth
or Earth’s shadow hits the moon, an
eclipse occurs.
 Eclipses occur when the moon’s
orbit which is usually tilted becomes
not tilted and the sun, moon and
Earth line up perfectly
