PHASES, ECLIPSES, AND
TIDES
• The changing relative positions of the
moon, Earth, and the sun cause the
phases of the moon.
• Phases-the different shapes of the
moon you see from Earth
– There are 8 phases
– The phase of the moon you see depends on
how much of the sunlit side of the moon
faces Earth
PHASES OF THE MOON
1. New Moon-The sunlit 5. Full Moon-The entire
side faces away from sunlit side faces Earth
Earth 6. Waning Gibbous-looks
2. Waxing Crescent-a almost full
small, crescent shape 7. Last Quarter-The
(fingernail) “other” half of the
3. First Quarter-Half of sunlit side faces Earth
the sunlit side faces 8. Waning Crescent-a
Earth small, crescent shape
4. Waxing Gibbous-looks (fingernail)
almost full
PHASES OF THE MOON
• Waxing-the sunlit, visible side of the
moon is “increasing” in size. You can see
more and more as it waxes.
• Waning-the sunlit, visible side of the
moon is “decreasing” in size. You can
see less and less as it “shrinks” or
wanes.
ECLIPSES
• The changing relative positions of the
moon, Earth, and the sun cause the
eclipses
• The moon’s orbit around Earth is
slightly tilted 5° relative to Earth’s
orbit around the Sun.
– This is the reason why in most months the
moon revolves around Earth without moving
into Earth’s shadow or the moon’s shadow
hitting Earth.
ECLIPSES
• When the moon shadow does hit Earth
or Earth’s shadow hits the moon, an
eclipse occurs
• Eclipse-When an object in space comes
between the Sun and a third object,
casting a shadow on that object.
– There are two types of eclipses: Solar and
Lunar
SOLAR ECLIPSES
• “Solar” is Latin for • Total Solar Eclipse-
“Sun” When the moon’s umbra
• When? Occurs when completely blocks light
the moon passes from the Sun from
directly between Earth hitting Earth
and the Sun, blocking • Partial Solar Eclipse-
sunlight from Earth When the moon’s
• A New Moon blocks your penumbra only partly
view of the Sun blocks light from the
• Penumbra-The larger Sun from hitting Earth
part of the moon’s • Umbra-The very
shadow. Part of the Sun darkest part of the
is still visible from moon’s shadow
Earth
LUNAR ECLIPSES
• “Lunar” is Latin for • Total Lunar Eclipse-When
“Moon” the moon is in Earth’s
umbra. Can be seen
• When? Occurs when anywhere on Earth that
Earth blocks sunlight the moon is visible (more
from reaching the likely to see a total lunar
rather than a total solar
moon eclipse
• Earth is directly • Partial Lunar Eclipse-
between the Sun and When the moon is in
a Full Moon Earth’s penumbra and
passes slightly into
Earth’s umbra. The most
common of all eclipses
TIDES
• The changing relative positions of the moon, Earth,
and the sun cause the tides
• Tides-The rise and fall of ocean water that occurs
every 12.5 hours or so
• Basically tides are caused by differences in how much
the moon’s gravity pulls on different parts of Earth
• At any one time on Earth there are two places with
high tides and two places with low tides on the
opposite sides of Earth from each other.
• As Earth rotates, one high tide stays on the side of
Earth facing the moon
• Each location sweeps through two high tides and two
low tides every 25 hours or so
TIDES
• Spring Tides-Spring tides are especially strong tides
(they do not have anything to do with the season
Spring). They occur when the Earth, the Sun, and the
Moon are in a straight line. The gravitational forces
of the Moon and the Sun both contribute to the
tides. Spring tides occur during the full moon and the
new moon.
• Neap Tides-Neap tides are especially weak tides.
They occur when the gravitational forces of the Moon
and the Sun are perpendicular (at right angles) to one
another (with respect to the Earth). Neap tides
occur during first quarter and last quarter moons.