Chapter 2: Earth’s Physical Geography Section 1: Our Planet, the Earth

The Earth and the Sun Galaxy: a family of stars – 4 Parts Earth Sun: center of everything for the Earth – 93 million miles away from Earth Planets Twinkling stars Our Galaxy is called the Milky Way – It is called this because the lights of the stars look like a trail of spilled milk across the sky

Days and Nights It takes 365 days, or 1 year, for the Earth to make a revolution around the sun Orbit: the oval-shaped path the Earth takes when it travels around the sun As the Earth rotates, it is day-time on the side facing the sun and night on the side facing away – Each rotation takes 24 hours. Axis: an imaginary line running through Earth which it turns on; runs between the North and South poles

Seasons The angle of the Earth’s axis causes either days to be longer than nights or nights to be longer than days The Earth’s tilt and orbit cause changes in temperature

Latitudes Spring/Fall Equinox: March 21 st /September 23 rd – The sun is directly over the Equator (O degrees) – One these dates, all over the Earth, the days are almost as long as nights Tropic of Cancer (23 ½ degrees North) – Summer solstice: June 21 st or 22 nd The sun shines directly above the Tropic of Cancer, making it the first day of summer for the Northern Hemisphere Tropic of Capricorn(23 ½ degrees South) – Winter solstice: December 21 st or 22 nd The sun shines directly above the Tropic of Capricorn, making it the first day of winter for the Northern Hemisphere

Latitudes (Cont’d) The season are reversed in the Southern Hemisphere Low latitudes: area between the Tropic of Cancer and the Tropic of Capricorn (near Equator) – Also called the tropics – Almost always very hot, lots of direct sunlight – Ex.: Islands – See textbook page 29. High Latitudes: regions lie between the Arctic and Antarctic Circles and the poles – Also called polar zones, because they are bitterly cold – Ex. : Alaska, Antarctica – Very little direct sunlight – Arctic Circle from degrees North to North Pole – Antarctic Circle from 66 ½ degrees South to South Pole

Latitudes (Cont’d) Middle Latitudes: receives fairly direct sunlight – Also called temperate zones – Four distinct seasons: spring, summer, fall,and winter