Introduction to the Earth

Mrs. Marquis

The Solar System

• Our solar system is part of the milky way galaxy

• Earth is one of 8 planets in our solar system

• The Sun is the central body of our solar system

• The Earth and other planets orbit around the sun in an elliptical

Our Solar System

• Image from www.aerospaceweb.org

The Solar System Cont…

• Milky Way Galaxy is one of at least 1,000,000,000 Galaxies in the universe.

• The universe is incredibly vast…beyond most of our comprehension.

• Many believe the universe began with a cosmic explosion “the big bang”– 12-15 billion years ago

The Spheres

• Lithosphere– Soil, rocks, landforms, etc.

• Atmosphere– Air and water above surface of earth

• Hydrosphere– The water in oceans, lakes, rivers, and aquifers– 77% of earth is covered by water

• Biosphere– All living things that occupy the earth

• plants & animals

The Spheres (picture from www.msu.edu)

LithospherePicture from www.uwsp.edu

Atmosphere• Picture from www.sponeil.org

Hydrosphere

• Picture from www.miami.edu

Biosphere

• Pictures from www.seashepard.com and www.dnr.wi.gov

Earth Movement

• ROTATION– The Earth moves through space as it spins on

its axis like a top.• Completes one rotation every 24hours.

• Spins from west to east.

• Sun appears to rise in the east and set in the west.

Rotation

• Image from www.berkely.edu

Earth Movement cont…REVOLUTION• The Earth takes 365 ¼ days to move around the sun

in nearly a circular path– The Earth is tilted as it moves.– The tilt means some places receive more direct

sunlight.• The Tropic of Cancer and the Tropic of Capricorn (23

½ degrees) receive the most direct sunlight.

RevolutionPicture from www.education.arm.gov

Solstices

Solstices• Summer solstice is around June 21

– the longest day in the Northern Hemisphere– N of 66.5 degrees experience 24 hours of daylight (Arctic

Circle) – S of 66.5 degrees S experience 24 hours of darkness

(Antarctic Circle)– Noon rays of sun are perpendicular to Tropic of Cancer

• 23.5degrees N

• Winter solstice is December 21 in the Northern Hemisphere

Equinoxes

• Equinoxes• March 20 Vernal (spring) Equinox• September 22 autumnal Equinox• “equal day and nights”

– Sun’s rays strike the equator at noon creating a 90 degree angle

• (See diagrams on page 18 of 10th edition)

*At all times the sun lights up about ½ of the earth

Standard Time

• At 1884 International Prime Meridian Conference the world was divided into 24 standard time zones– Each extended over 15 degrees longitude– Greenwich (prime) meridian chosen as standard

for the system– Greenwich Mean Time (GMT) now called

Universal Time Coordinated (UTC)

Standard Time Zones

• Picture from www.uwsp.edu

Standard Time-The U.S.

• Eastern Standard Time (UTC – 5)

• Central Standard Time (UTC-6)

• Mountain Standard Time (UTC-7)

• Pacific Standard Time (UTC-8)

• Alaska Standard Time (UTC-9)

• Hawaii Standard Time (UTC-10)

Us Time Zones

Day Light Savings Time• Purpose was to conserve energy during

WWI– Germans ordered clocks forward 1 hr– Reduced energy use of citizens

• US began similar policy in 1918, not everyone observed it– Uniform Time Act forced all states to comply

except Hawaii and parts of Indiana and Arizona

• Many other nations have followed

Picture from www.lanl.gov