How are the motions and positions of Earth and the Sun connected to what

happens on Earth?• Earth’s rotation on its axis determines the

length of the day.

• Earth’s orbit around the Sun determines the length of the year.

• The tilt of Earth’s rotational axis with respect to the plane of Earth’s orbit causes the seasons.

The changing phases of the Moon originally inspired the concept of the month

Moon Phase Names• New Moon• Waxing Crescent• First Quarter• Waxing Gibbous• Full Moon • Waning Gibbous• Third Quarter• Waning Crescent

Watch Movie at:http://antwrp.gsfc.nasa.gov/apod/image/9911/lunation_ajc.gif

The Causes of Moon Phases

• Think to yourself about the answer to this question:

What causes the phases of the Moon?

Take out a piece of paper and quickly write out a brief answer.

How long does it take to complete the full cycle of Moon Phases?

A. About a dayB. About a weekC. About a monthD. About a yearE. None of the above

Check your answer with your partner!!

Although the Moon is always

½ lit by the Sun, we see

different amounts of the lit portion from

Earth depending on

where the Moon is

located in its orbit.

Let’s Watch some Moon Phase Animations!

Pay attention to where the Moon, Sun and Earth are located and how the Moon appears from Earth at each of these positions.

Look at how much of the Moon is illuminated when at each position.

Look at which side of the Moon is illuminated when at each position.

Although the Moon is always

½ lit by the Sun, we see

different amounts of the lit portion from

Earth depending on

where the Moon is

located in its month-long

orbit.

How many phases shown in the picture at the right will the Moon go through in one day?

How long does it take the Earth to complete one rotation? How far will the Moon have moved?

How long does it take the Moon to complete one orbit? How many of the phases will the Moon have gone through in this time?

How much of the Moons total surface is illuminated when it is in the New Phase? Full Phase?

How much of the illuminated surface of the Moon is visible from Earth when it is in the First Quarter Phase, Full Phase?

What time is it when the Waxing Gibbous Phase is highest in the sky, Rising? Setting? What phase will it be in one week later….

What time is it when the waxing

crescent moon is highest in the

sky? When does it first

rises? When does it set?

East

West

What time is it when the waxing

crescent moon is highest in the

sky? When does it first

rises? When does it set?

East

West

What time is it when the waxing

crescent moon is highest in the

sky? When does it first

rises? When does it set?

East

Wes

t

What moon phase would be

rising in the East at 3pm?

What Moon phase would be

setting in the West at 3pm?

East

West

The Moon Phase is highest in the sky at 9pm today. What phase will the Moon be in three weeks after today?

Which Moon position (A-E), shown in the diagram at right, best corresponds with the moon phase shown below?

Sun

Orbit of the Moon

Ear

th

A

B C

D

E

If the Moon were in the phase shown above, what phase would it be in two weeks later?

Which of the situations shown above occurs at a time closest to sunset?

If the moon is in the Full phase today, how many of the moon phases shown above would the moon go through during the next 11 days.

A. only oneB. twoC. threeD. more than threeE. none

Which of the following groups of moon phases can be seen (above the horizon) at 3:00 am?

A. Third Quarter, Waning Crescent, and Waxing CrescentB. New Moon, First Quarter, and Waxing GibbousC. Third Quarter, Full Moon, Waning GibbousD. Waxing Crescent, First Quarter, Waxing GibbousE. None of the above is correct

HW#3 – Moon Phases, on Masteringastronomy, assigned February 1st Due February 8th

Practice Problems – Moon Phases RT’s available on D2L