1. Earth, Sun, Moon System
Next Generation Science Standards.
Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons.  [Clarification Statement: Examples of models can be physical, graphical, or conceptual.]

2. Equator is 0 Poles are 90 N and 90 S
Latitude denotes distance north or south of the equator.
Lines run parallel to one another.
“latitude flatitude”
Equator is 0
Poles are 90 N and 90 S

3. Prime Meridian goes through England
Longitude lines run from N to S poles.
Closer at the poles, farther from each other at the equator.
These lines intersect latitudes at right angles.
Prime Meridian goes through England

4. The Equator divides the globe into northern and southern hemispheres.

5. This is called Earth’s obliquity
Earth is tilted at 23.5 o
This is called Earth’s obliquity

7. Arctic Circle and Antarctic Circle 23.5 o north and south of the poles
Within the circles formed by these latitudes, earth receives 0 or 24 hrs of sunlight twice a year.
Arctic Circle and Antarctic Circle o north and south of the poles

8. Sun’s rays make a 90 o angle
The latitudes at which
Sun’s rays make a 90 o angle
With Earth’s surface.
Other special lines of latitude:
Tropic of Cancer and Tropic of Capricorn
23.5 o north and south of the Equator

9. Looking at the North Pole - counterclockwise
Looking at the South Pole - clockwise

10. The Earth’s rotation causes us to experience what phenomena?

11. The Earth’s rotation causes us to experience what phenomena?
Day and Night

12. Given that the sun “rises” in the east, about what time of day is it in location A, B, C, and D?
Sun’s rays C

13. Which diagram accurately shows the direction of Earth’s spin from the North Pole?B N N

14. Because of Earth’s tilt.
Why does daylight last for different amounts of time at different times of the year?
Because of Earth’s tilt.

15. Does the sun rotate?

16. Which orbit most accurately shows Earth’s path around the sun?
(Keep in mind the Earth is on average 107 sun-diameters away from the Sun)

17. This does not cause seasons!
At its nearest point, Earth is 147,500,000 km from the sun.
At its farthest point, it is 152,600,000 km from the sun.
This is less than 3 % difference from nearest to farthest point.
(NASA.gov) A
To the eye, the orbit would appear as shown,
This does not cause seasons!

18. Some planets have more of an ellipse than others.
Perihelion – when a planet is closest to sun.
Aphelion – when a planet is farthest from sun.
dotted line - perfect circle
solid line actual planet path
+ = sun

19. The line around the earth that divides light from dark is the circle of illumination.

20. The angle at which sun’s rays hit the Earth is the angle of incidence.

21. Think: How many degrees above the equator is the most direct sunlight?
Earth in June
The Northern Hemisphere is tilted towards the sun creating more hours of day light = summer.
The Southern Hemisphere is titled away from the sun creating fewer hours of day light = winter.
Think: How many degrees above the equator is the most direct sunlight?

22. Earth in December
The Northern Hemisphere is titled away from the sun creating fewer hours of day light = winter.
The Southern Hemisphere is tilted towards the sun creating more hours of day light = summer.

23. Autumnal/ Vernal Equinox
Summer solstice
Winter solstice
Autumnal/ Vernal Equinox
The Analemma

24. Solstices When the sun’s direct light is farthest from the equator.
The sun’s direct light reaches its greatest distance north of the equator once each year.
The sun’s direct light reaches its greatest distance south of the equator once each year.
In the Northern Hemisphere
Summer solstice
June
“longest day of the year”
Winter solstice
Dec 21 or 22
“shortest day of the year”

25. Equinox
Equinox - when the noon sun is directly overhead at the equator.
Day and Night are each 12 hours long.
Happens twice a year:
Occurs March 21st (start of spring, NH)
Occurs Sept. 22nd (start of fall, NH)

27. not to scale.... and ellipse is exaggerated!

29. How long does it take the Earth to complete its orbit around the sun?
days
Every 4 years, an extra day is added to the calendar!
Next leap year: 2016

30. How long does it take the sun to revolve around the milky way?
200,000,000 years!
If the Earth is 4.6 billion years old, how many times has it followed its orbit around the milkyway galaxy?