1. Unit 3: Earth in the Universe
In this unit, we will understand the earth, moon, and sun systems and the properties, structures and predictable motions of celestial bodies in the Universe.

2. Unit 3: Earth in the Universe
By the end of the this unit, students will be able to:
Explain how the relative motion and relative position of the sun, Earth, and moon affect the seasons, tides, phases of the moon, and eclipses.
Explain why Earth sustains life while other planets do not based on their properties (including types of surface, atmosphere and gravitational force) and location to the Sun.
Summarize space exploration and the understandings gained from them.

3. Astronomy
Astronomy: study of the moon, stars, and other objects in space. Axis: the imaginary line passing North to South through Earth’s center allowing it to tilt 23.5 degrees. Orbit: is the path Earth follows around the Sun.

4. How Earth Moves
Earth moves through space in two major ways: Rotation Revolution Rotation: * the spinning of Earth on its axis. * takes Earth about 24-hours to rotate once. * creates day and night.

5. How Earth Moves
Revolution: * the movement of one object (Earth) around another (sun). * one complete revolution is a year.

6. Leap Year It takes days for Earth to go around the sun one time. This means we are not at the same place in our orbit as we began. Because 0.24 equals about ¼ of a day, we add a day to our calendar every 4 years. This year (2016) was a leap year so we had a February 29th. Our next February 29th will be in 2020.

7. In your notebook . . .
Draw a Diagram showing Earth’s Revolution around the sun.

8. Motions of the Moon The moon moves through space in two ways:
Revolves around Earth
Rotates on its own axis.
It takes the moon about 27.3 days to revolve around Earth.
The same side of the moon always faces the Earth.

9. Motions of the Moon
The moon does not produce the light you see; the moon reflects light from the sun. As the moon revolves around the Earth, the relative positions of the moon, Earth, and sun change. The changing positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.

10. Phases of the Moon
The phase of the moon you see depends on how much sunlit side of the moon faces Earth.
Waxing: As the moon revolves
around the Earth, more and
more of the lighted side of the
moon is seen until the side
of the moon you see is fully lit.
(if light is on right, moon is waxing)
Waning: As moon continues
in its orbit, you see less and
less of the lighted side.
(if light is on left, moon is waning)

11. Phases of the Moon
Phases: the different shapes of the moon you see from Earth.
Gibbous: growing or bulging; humpback
Crescent: curved with points on the ends
Remember, the moon does not produce the light you see; the moon reflects light from the sun.

12. In your notebooks . . .
Please draw and label the phases of the moon as seen from Earth.

13. Eclipses
Eclipse: cover up; when the moon’s shadow hits Earth or Earth’s shadow hits the moon Are named by which object’s light is being covered up or blocked from your view.

14. Eclipses
Solar Eclipse: the moon passes directly between Earth and the sun, blocking sunlight from Earth.

15. Eclipses
Lunar Eclipse: Earth blocks sunlight from reaching the moon.

16. Tides
Tide: the rise and fall of ocean water that occurs every 6 hours. Tides mainly happen because water on Earth is pulled by the gravity of sun and moon.

17. Tides
High Tides: The moon’s gravity causes high tides on the side closest to the moon and on the opposite side. Low Tides: occurs between the two high tides.

18. Tides
Spring Tide: tide with greatest difference between low and high tides; higher than normal tides.
Gravity of sun and moon pull in the same direction.
Occurs when Earth, the sun, and the moon are in a straight line; therefore spring tides occur at New moon and Full moon.

19. Tides
Neap Tides- tide with the least difference between consecutive low and high tides.
Occurs when the moon is at a right angle to the sun; therefore neap tides occur at first quarter moon or last quarter moon.

20. Video: Tides
goo.gl/jm1XcZ

21. Seasons on Earth
Most places outside tropics and polar regions have four distinct seasons: Winter, Spring, Summer, and Autumn.
Why is it generally warmer near the equator than near the poles?
Sunlight hits Earth’s surface most directly near the equator.
Why is it generally colder near the poles than equator?
Near the poles, sunlight arrives at a steep angle so it is spread out over a greater area.

22. What causes seasons on Earth?
The tilt of the Earth’s axis as it revolves around the sun causes seasons on Earth.
The North end of its axis is tilted away from the sun for part of the year. When north end of axis is tilted away from the sun, Northern hemisphere has winter.
The North end of its axis is tilted toward the sun for part of the year. When north end of axis is tilted toward the sun, North hemisphere has summer.

23. Seasons on Earth
If Earth’s axis were straight up and down relative to its orbit, temperatures would remain fairly constant year-round.

24. Seasons on Earth
Solstices: when the noon sun is overhead at either the Tropic of Cancer of the Tropic of Capricorn.
Occur twice a year: Summer solstice: June 21 (longest daylight of the year) Winter solstice: December 21 (shortest daylight of the year)

25. Seasons on Earth
Equinox: halfway between the solstices; the noon sun is directly overhead at the equator; day and night are of equal length. Occur twice a year: Vernal Equinox: March 21 Autumnal Equinox: September 22