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
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
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 and the tides are HIGHER than normal Neap Tide – When the moon and sun are at right angles and the 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.
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 moon 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