Transcript The Earth in Space

The Earth in Space
Solar System
In the Milky Way Galaxy
100,000 light years wide
1 ly = 5,878,625,373,183 miles
What does the sun provide for earth?

Light and solar energy
• Closest star = 4.22 ly
The Earth
• Voyager 1 = 14 light hours away;
took 32 years (1977) to get there
- .0017 ly away
- 38,400 mph
It is not a perfect sphere

It’s fatter at the equator and the poles are
squished: difference of 26.58 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:
Sextillion
6,600,000,000,000,000,000,000 tons or
1,320,000,000,000,000,000,000,000 lbs
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?
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!
147,000,000 km
152,000,000 km
Not to scale!
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
Seasons
N Pole
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)
24
Atlanta
18/6
12/12
12/12
12
12/12
24
6/18
Solar Lines on Earth
Arctic Circle
Tropic of Cancer
Equator
Tropic of Capricorn
Antarctic Circle
24 hrs. daylight
Summer
Direct Solar Energy
Winter
Not to scale!
24/0
12/12
12/12
12/12
24
12
24
At the North Pole
0/24
Svalbard, Norway: Daytime from April 19 to August 23!!!
3 hr time period
Extremes: 20 hours at the Circles, 186 days at the poles
Spring
or
Fall
Winter
Direct Solar Energy
Summer
24 hrs. daylight
Not to scale!
Not to scale!