Lunar Phases
A Lunar month takes
29.5 days to complete
from New Moon to New
Moon. The Moon’s orbit around the Earth
takes 27.5 days to
complete.
Moon Phases and Tides
Lunar Eclipse
may occur
during some
Full Moon
Phases
The Moon rotates on
it’s axis at the same
rate that it revolves
around the Earth in it’s
orbit. Tidal forces from
the Earth pull on the
Moon so that the same
side of the Moon is always facing Earth.
Earth only sees one
side of the Moon, but
all of the Moon’s surface receives solar radiation during a lunar
month so there really
is no “dark side” of the
Moon, only the far side
of the Moon that Earth
does not get to see.
Time for Lunar Orbit =
27.5 days
Time for Lunar Cycle
(phases) = 29.5 days
Apollo 11—July 20, 1969
First Moon Landing
Full Solar Eclipse
occurs sometimes
during a New Moon
Why do we see phases
of the Moon?
The Sun illuminates the
Moon’s surface as the
Moon revolves around
the Earth. This change
in the illuminated surface
of the Moon is called the
lunar cycle. This cycle
has eight different phas-
Moon Phase Diagram
Tides
Tides occur when two bulges of
water form in Earth’s oceans on
opposite sides of the planet. The
Moon’s gravitational force pulls and
creates one bulge of water and the
Earth’s rotation on it’s axis
(centrifugal force) pushes the
bulge on the opposite side.
High tides is when the sea level
reaches its highest level. This is
the large bulge of water. Low tide
when the sea level reaches its lowest level. This is the place on
Earth without the tidal bulge.
The Sun’s gravitational pull also
causes tidal forces, but they are
less powerful than the Moon’s .
Spring Tides occur when the Sun,
Earth, and Moon are in alignment.
The highest high and lowest low
tides occur during this arrangement when there is a New or Full
Moon.
Neap Tides occur when the Moon
to Earth angle is 90° or perpendicular. During this time (mostly at
First and Last Quarter Moons) tides
are not as extreme as during
Spring Tides.
Tide Chart for
Galveston Texas
How many high
and low tides occur during one 24
hour period?
This changes due
to the geographic
location of the
coastline.