moon phases

MOON PHASESPOWERPOINT

2

• The Moon orbits the Earth

• The Moon doesn’t shine on its own; it reflects sunlight

Important Key Points

The revolution of the moon around the Earth causes the moon to appear to have phases.

NSF North Mississippi GK-8

Why does the moon have phases?

The lunar month is the 29.5 days it takes to go from one new moon to the next. During the lunar month, the Moon goes through all its phases.

FULL

QUARTER

CRESCENT

GIBBOUS

FOUR MAIN SHAPES

Waxing or Waning?

Waxing means the moon is “growing”. If the moon is getting bright from the right it is waxing.

Waning means the moon is “shrinking”. If the moon is dark on the right it is waning.

Lunar Cycle: TEKS 8.7B

Moon Phases


How can I determine which phase the moon is in?

• Step 1: Look at which side is illuminated. – If the right side is illuminated then it is waxing. – If the left side is illuminated then it is waning. – Or if all is illuminated then it is a full moon– If there is no illumination then it is a new moon.

• Step 2: Look at the shape and decide if it is full, quarter (half moon), crescent (less than half) or gibbous (more than half).

**Note, a waxing quarter is called 1st Quarter. A waning quarter is called 3rd Quarter.


Let’s practice!• Step 1: Look at which side is illuminated.

– If the right side is illuminated then it is waxing.

– If the left side is illuminated then it is waning. – Or if all is illuminated then it is a full moon– If there is no illumination then it is a new

moon. • Step 2: Look at the shape and decide if it is

full, quarter (half moon), crescent (less than half) or gibbous (more than half).

Step 1—The left side is light, so it is waning.Step 2—The shape is less than half, so it is crescent

The moon phase is a WANING CRESCENT


Let’s practice!• Step 1: Look at which side is illuminated.

– If the right side is illuminated then it is waxing.

– If the left side is illuminated then it is waning.

– Or if all is illuminated then it is a full moon– If there is no illumination then it is a new

moon. • Step 2: Look at the shape and decide if it is full,

quarter (half moon), crescent (less than half) or gibbous (more than half).Step 1—The left side is light, so it is waning.

Step 2—The shape is half, so it is quarter.

The moon phase is a 3rd QUARTER.


• Which phase is shown here?

On Your Own Example 1


What causes TIDES?

•There are two high tides and two low tides each day. • Tides are caused by the pull of both the moon’s gravity and the sun’s gravity on the Earth. The moon has a 70% effect on the tides and the sun has a 30% effect on the tides.•Changes in the positions of the Earth, sun, and moon affect the height of the tides throughout the month.

Important Key Points

During full or new moons, the Earth, sun, and moon are nearly in a straight line. This occurs twice each month.

The gravitational pull of the sun is "added" to the gravitational pull of the moon on Earth, causing the oceans to bulge a bit more than usual.

This means that high tides are a little higher and low tides are a little lower than average.

Spring Tides

The top picture is low tide and the bottom is high tide.

Notice that there is a BIG difference between the two.

Spring Tides

Seven days after a spring tide, the sun and moon are at right angles to each other and produce neap tides. These occur twice each month.

Neap tides occur during the first and third quarter moon, when the moon appears "half full.“

When this happens, the bulge of the ocean caused by the sun partially cancels out the bulge of the ocean caused by the moon.

This produces moderate tides meaning that high tides are a little lower and low tides are a little higher than average.

Neap Tides


The top picture is low tide and the bottom is high tide.

Notice that there is only a small difference between the two.

Neap Tides

moon phases

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