Do Now (In Notebooks)  Where did the Earth’s Moon come from?  What is the biggest effect the moon has on Earth?

Essential Question What if there was no moon? Objectives Students will be able to: Describe formation theories of the moon Describe how the moon affects tides Identify the phases of the moon Provide the mechanism for eclipses Differentiate between solar and lunar eclipses

Where did the moon come from?  There are three theories of the moon’s formation:  Capture Theory  Simultaneous Formation Theory  Impact Theory

Capture Theory  Moon caught by Earth’s gravitational pull  Problems:  What slowed the Moon?  Why are the compositions so similar?

Simultaneous Formation Theory  Moon and Earth formed at same general time in same general area  Problem:  Why does Earth have so much more iron?  Why doesn’t the moon have water like the Earth?

Impact Theory  Earth collided with a Mars-sized object  Materials from collision came together to form moon  Explosion evaporated water

The Moon’s Features  Highlands  Areas light in color  Mountainous  Maria  Dark smooth regions  From Eruptions  Impact craters  Regolith  Loose, ground up rock  Radius km  About 1/4 th of Earth’s

How does the Moon affect us?

Tides  Periodic rise and fall of the level of the ocean  The moon’s gravity pulls on Earth  Gravity creates build up of ocean water on both near and far sides of the Earth

 The ocean water build up stays in line with the moon  The ocean level rises and falls every 12 hours

Tidal Range  Vertical distance between low and high tide  1- 2 m on East Coast of North America  Bay of Fundy – 20 meters

Tides  Semidiurnal Tide  2 high tides and 2 low tides in 24 hours  Diurnal Tide  one high tide and one low tide in 24 hours

The Sun’s Effect  Spring Tide  When the sun and moon are aligned  Tides are HIGHER than normal  Neap Tide  When the moon and sun are at right angles  Tides are LOWER than normal

Sun vs. Moon  Does the Sun or the Moon have a larger effect on tides? THE MOON!! *Even though the moon is smaller than the Sun, the moon is much closer to the Earth, and therefore has a larger effect on the tides.

Do Now – In Notebooks  What is the most likely theory of the Moon’s formation?  Draw the Sun, Earth, and Moon as they are arranged during a neap tide.

Phases of the Moon What if there was no moon?

What causes the moon’s phases?  The moon does not emit visible light  The moon is visible due to reflected sunlight  One side (1/2) of the moon is always lit  As the moon rotates around Earth, the light reflected by the moon changes, causing phases

Phase Names  Gibbous  Crescent  Quarter moon  Full Moon  New Moon

Waxing Vs. Waning  Waxing  Increase in visible, sunlit portion of the moon  “Right” side of moon is visible  Waning  Decrease in visible, sunlit portion of the moon  “Left” side of the moon is visible

Phase Names  Waxing Crescent  First Quarter  Waxing Gibbous  Full Moon  Waning Gibbous  Third Quarter  Waning Crescent

Eclipses What if there was no moon?

Eclipses  One object moves into the shadow of another  Named for the celestial body that is blocked

Lunar Eclipse  Moon passes into Earth’s shadow  Reflected light from the sun is blocked, instead moon seems red  Can only occur during full moon  Occur slightly more frequently than solar

Solar Eclipse  Moon passes between Earth and Sun  Only see outer layers of sun  Occurs during new moon

Regions of Solar Eclipse  Umbra  Area does not receive sunlight, total eclipse  Penumbra  Receives partial sunlight, partial eclipse

Why don’t we have monthly eclipses?  The moon’s orbit is tilted compared to Earth  Eclipses only occur when orbits line up