The Phases of the Moon

Is the Earth’s shadow is the cause of the Moon’s phases?

NO

True Scale of Earth-Moon System:

Moon Takes About a Month (29.3 days) to go through all phases

Phases:

• New – Whole face is dark• Crescent – Looks like fingernail• First & Third Quarter -- Half lit• Gibbous – Latin gibbosus humpbacked• Full – Face is totally lit up

• Waxing – Getting Stronger (“wax poetic”)

• Waning – Getting Weaker (“on the wane”)

Moon Phases

Phases caused by Moon’s orbit around Earth

The time the moon is high above the southern horizon depends on what

phase it is in.;

When is the third quarter moon directly overhead?

• A. 6 AM• B. Noon• C. 6 PM• D. Midnight

When is the waxing crescent directly overhead?

• A. 9 PM• B. 3 AM• C. 9 AM• D. 3 PM

What time does the full moon rise?

• A. 6 AM• B. Noon• C. 6 PM• D. Midnight

The moon is full on March 30. What constellation is it in?

• A. Taurus• B. Virgo• C. Capricornus• D. Gemini

The Sun is in Gemini. You observe the moon is in Cancer. What phase is the moon in?

The zodiacal constellations in the order the sun and moon pass through

• Pisces• Aries• Taurus• Gemini• Cancer• Leo• Virgo• Libra• Scorpius• Sagittarius• Capricornus• Aquarius

A. first quarterB. third quarterC. waning crescentD. waxing crescentE. full

True Scale of Earth-Moon System:

Eclipses

Eclipses occur when Sun, Earth, Moon are in Syzygy (i.e. all three are in a line)

Moon in middle =“Solar eclipse”Earth in middle =“Lunar Eclipse”

• It is an eclipse of whatever body appears dark as seen from earth

Partial Eclipse – Moon not lined up to block out whole sun

Eclipse movie (click to start)

Where an Eclipse looks

Total, andWhere it

Looks Partial:

Annular Eclipse = Moon too far away to eclipse whole sun

During a solar eclipse, the moon must be in the ____ phase.

• A. Full• B. New• C. Crescent• D. Gibbous• E. First Quarter

Lunar Eclipse: Shadow of Earth Falls on Moon

During a lunar eclipse, the moon must be in the ____ phase.

• A. Full• B. New• C. Crescent• D. Gibbous• E. First Quarter

Moon’s orbit is tilted 5 degrees from the ecliptic plane

If the moon’s orbital plane was the same as the ecliptic plane, eclipses:

• 1. Would occur more often• 2. Would occur less often • 3. Would occur at the same rate

Eclipses would occur more often.Currently, can only occur when moon is at

“nodes” (where moon’s path crosses ecliptic)

If you were on the moon, you would see Earth go through phases.

What phase is the Moon in?1. New, 2. Cresc, 3. Quarter

4. Gibbous 5 Full

The Sun is in Pisces. You observe a first quarter moon. What constellation is it in?

The zodiacal constellations in the order the sun and moon pass through

• Pisces• Aries• Taurus• Gemini• Cancer• Leo• Virgo• Libra• Scorpius• Sagittarius• Capricornus• Aquarius

A. PiscesB. GeminiC. VirgoD.Sagittarius

The Sun is in Gemini. You observe a total lunar eclipse. What constellation is the moon in?

The zodiacal constellations in the order the sun and moon pass through

• Pisces• Aries• Taurus• Gemini• Cancer• Leo• Virgo• Libra• Scorpius• Sagittarius• Capricornus• Aquarius

A. PiscesB. GeminiC. VirgoD.Sagittarius

The moon is in the middle of a lunar eclipse on March 30. What

constellation is it in?• A. Taurus• B. Virgo• C. Capricornus• D. Virgo