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Bellringer

Bellringer. How many forces are acting on a baseball that is thrown by a pitcher?. Phases, Eclipses, and Tides. Notes. Lunar Motions. Our moon’s name = Luna The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.

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Bellringer

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  1. Bellringer • How many forces are acting on a baseball that is thrown by a pitcher?

  2. Phases, Eclipses, and Tides • Notes

  3. Lunar Motions • Our moon’s name = Luna • The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides. • Luna revolves around the Earth. It takes the moon about 27.3 days to revolve around Earth once. • As Luna and Earth move, their positions change in relation to each other. Their positions also change in relation to the sun.

  4. Lunar Motion • Our moon it tidally locked with Earth. • This means that the moon’s day is the same as its year. It takes one month to rotate on its axis and one month to complete one revolution around Earth. • Because of this, only one side of Luna faces Earth. The other side is ALWAYS facing away from Earth. • There is no such thing as the “dark side” of the moon, but there is a “far side.”

  5. Lunar Phases • The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth. • The moon does not give off its own light. The moon reflects light from the sun. • Question: How much of the moon is ALWAYS lit up by the light from the sun? • Question 2: How much of every object in this solar system is ALWAYS lit up by the sun?

  6. Phases of the Moon • The moon appears to have different shapes at different times. These different shapes of the moon that you see are called phases.

  7. Lunar Phases • As the moon revolves around Earth, you see the moon from different angles. You cannot see all of the half of the moon that is lit by the sun. • http://upload.wikimedia.org/wikipedia/commons/c/c0/Lunar_libration_with_phase2.gif

  8. Lunar Phases • New Moon • Waxing Crescent • First Quarter • Waxing Gibbous • Full Moon • Waning Gibbous • Third Quarter • Waning Crescent • Waxing - Getting Bigger (wax on) • Waning - Getting Smaller (wane off) • Crescent - less than 1/4 visible • Gibbous - more than 1/4 visible • All 8 phases occur within about one month’s time.

  9. Eclipses • Eclipse - to cover up • When Luna’s shadow hits Earth or Earth’s shadow hits Luna, an eclipse occurs. A solar eclipse occurs when the moon passes directly between Earth and Sol, blocking sunlight from Earth. • An eclipse is when an object in space comes between the sun and another object.

  10. Eclipses • Sometimes the moon moves between Earth and Sol. The moon blocks sunlight from reaching Earth (this means the moon is casting its shadow onto the surface of Earth). A solar eclipse occurs when an NEW MOON blocks your view of the sun.

  11. Eclipses • A lunar eclipse occurs when Earth is between Luna and Sol. • In a lunar eclipse, Earth’s shadow hits the moon. • A lunar eclipse occurs when there is a FULL MOON.

  12. Eclipses • So why is there not a solar and lunar eclipse each time we have a NEW MOON and FULL MOON? • The moon does not lie in a straight line between Earth and Sol. It is tilted about 5° from the ecliptic. Because of this tilt, eclipses are much rarer than expected. • http://eclipse.gsfc.nasa.gov/eclipse.html

  13. Tides • Tides are caused mainly by differences in how much Luna’s gravity pulls on different parts of Earth. • Tides are the regular rise and fall of ocean water. The ocean waters rise for about 6 hours a day, and fall for about 6 hours a day. Therefore there are two high tides and two low tides every 24 hours. • Luna’s gravity causes tides. The force of the moon’s gravity causes ocean water on Earth to move higher in some places and lower in other places. • Sol’s gravity also pulls on Earth’s ocean waters.

  14. Tides • During a NEW MOON, Sol, Earth, and Luna are lined up in a straight line. The combined forces of the sun and the moon cause spring tides. A spring tide is the highest possible high tide. • Sometimes the sun, moon, and Earth form a right angle (90°). This arrangement occur at the FIRST and THIRD QUARTER moons, and produces a neap tide. A neap tide is the lowest possible high tide.

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