1. The Earth in Space

2. Solar System In the Milky Way Galaxy
What does the sun provide for earth?
Light and solar energy
100,000 light years wide
1 ly = 5,878,625,373,183 miles

3. The Earth It is not a perfect sphere
Closest star = 4.22 ly
Voyager 1 = 14 light hours away; took 32 years (1977) to get there ly away ,400 mph
The Earth
It is not a perfect sphere
It’s fatter at the equator and the poles are squished: difference of miles
We are about 93,000,000 miles from the sun (it takes 8 minutes for sunlight to reach us!)
The Earth weighs 6,600 billion billion tons:
6,600,000,000,000,000,000,000 tons or
1,320,000,000,000,000,000,000,000 lbs
Sextillion

4. Earth’s Rotation The Earth rotates on an axis
One rotation = 23 hrs., 56 min., 4 sec. = 1 day
Rotates eastward
We rotate at more than 1000 mph!
Why don’t we feel a 1000 mph wind?
What would happen if we didn’t rotate?

5. Earth’s Revolution
The Earth revolves around the sun in an oval shaped orbit
Closest to sun = in December!
1 revolution = 365¼ days = 1 year
We add 1 day in February every 4 years
= Leap Year
Next one is 2012
We move at 66,700 mph around the sun!

6. 147,000,000 km
152,000,000 km
Not to scale!

7. Earth’s Tilt The Earth is tilted 23½º off parallel from the sun
The poles always point to the same spot in space
North pole points to the North Star
This tilt causes the seasons

8. Seasons Solstice Equinox Longest / shortest day of the year
N Pole
Solstice
Longest / shortest day of the year
When one pole is ‘pointing’ towards the sun
Summer (June) and winter (Dec)
Equinox
Equal length day and night
When both poles are equidistant from sun
Spring/Vernal (March) and fall/Autumnal (Sept)

9. Daylight
Atlanta 24
18/6
12/12
12/12
12/12 12
6/18 24
Darkness

10. Solar Lines on Earth Arctic Circle Tropic of Cancer Equator
Tropic of Capricorn
Antarctic Circle

11. Summer Winter 24 hrs. daylight Direct Solar Energy 24 hrs. darkness0º
24 hrs. daylight
Summer
Direct Solar Energy
Winter
24 hrs.
darkness
Not to scale!

13. Daylight At the North Pole Darkness 24 24/0 12/12 12/12 12/12 12 24
0/24

14. Svalbard, Norway: Daytime from April 19 to August 23!!!
3 hr time period
Extremes: 20 hours at the Circles, 186 days at the poles

15. 66½º N
23½º N
23½º S
66½º S 0º
Spring or
Fall

16. Winter Summer 24 hr. darkness Direct Solar Energy 24 hrs. daylight0º
Winter
Direct Solar Energy
Summer
24 hrs. daylight
Not to scale!

17. Not to scale!