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 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:6,600,000,000,000,000,000,000 tons or1,320,000,000,000,000,000,000,000 lbs

• Closest star = 4.22 ly

• Voyager 1 = 14 light hours away; took 32 years (1977) to get there - .0017 ly away - 38,400 mph

Sextillion

Earth’s Rotation

The Earth rotates on an axisOne rotation = 23 hrs., 56 min., 4 sec. = 1 dayRotates eastwardWe 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 yearWe 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

SeasonsSolstice 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)

N Pole

N Pole

Darkness

Dayligh

t

12

24

24

18/6

12/12

6/18

12/1212/12

AtlantAtlantaa

Solar Lines on EarthArctic Circle

Tropic of Cancer

Equator

Tropic of Capricorn

Antarctic Circle

66½º N

23½º N

23½º S

66½º S

0º

Not to scale!

Direct Solar Energy

24 hrs.

darkness

SummeSummerr

WinteWinterr

24 hrs. daylight

Darkness

12

24

24

24/0

12/12

0/24

12/1212/12

At the North At the North PolePole

Dayligh

t

Svalbard, Norway: Daytime from April 19 to August 23!!!

Extremes: 20 hours at the Circles, 186 days at the poles

3 hr time period

66½º N

23½º N

23½º S

66½º S

0º

SprinSpringg

oror

FallFall

66½º N

23½º N

23½º S

66½º S

0º

WinterWinter

SummeSummerr

Not to scale!

Direct Solar Energy

24 hr.

darkness

24 hrs. daylight

Not to scale!