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Moon Phases & Eclipses

Objectives

• Why does the Moon have phases

• How do the Earth and Moon affect each other

• What are eclipses

Why Does the Moon Look

Like That ?!?!?

The Moon Orbits the Earth• Does the Moon give off

its’ own light?

• Half of the Moon is always lit up by the Sun-we see parts of that half.

• The Moon reflects Sunlight

• Its appearance depends on the relative geometry of the earth-sun-moon system

Moon light comes from_____

A. Reflected light from Earth

B. Reflected Sun light

C. Light produced by the Moon

D. Lots of Moon people with flash lights

Q: You see a full Moon on the Meridian. About what time is it?

A) 12:00 AM (midnight)

B) 6:00 PM

C) 12:00 PM (noon)

D) 6:00 AM

Q: It’s about 6:00 PM local time. You look up and see the Moon is crossing your meridian. What phase is it in?

A) Waning crescent

B) 1st quarter

C) 3rd quarter

D) Waxing gibbous

Q: You see a full Moon on the western horizon. About what time is it?

A) 12:00 AM (midnight)

B) 6:00 PM

C) 12:00 PM (noon)

D) 6:00 AM

LT

The Cause of Moon Phases

• Pg 81

Predicting Moon Phases

• Pg 85

Solar System Distances

Elongation Angle!!!

Laser Distance

McDonald Observatory, TX

Moon

D=384,000 km

Eclipses

Solar Eclipse: The moon passes between the Sun and Earth

Lunar Eclipse: The Earth passes between the Moon and the Sun

Why don’t we see a solar and lunar eclipse every month?

Moon-Earth-Sun Geometry

How likely are Eclipses?

~5°

Ecliptic

moonSun

Lunar Eclipse

Penumbra

Solar Eclipse

Total Solar Eclipses

Laramie!!!

• Lunar eclipses only occur during the _____ Moon phase, and solar eclipses only occur during the _____ Moon phase.

A) Full, 1st quarter

B) New, Full

C) New, 3rd quarter

D) Full, New

Observing tonight???