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# The Earth in Space.

## Presentation on theme: "The Earth in Space."— Presentation transcript:

The Earth in Space

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

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

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 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)

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

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

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

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

66½º N 23½º N 23½º S 66½º S Spring or Fall

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

Not to scale!

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