Eratosthenes ( BCE) Determined absolute distances from sun to earth by measuring earth’s circumference. Made first map of earth with lines of longitude and latitude.

Facts About the Earth Formed about 4.5 billion year ago – same time as the sun and other planets Early atmosphere had no oxygen – mostly N 2, CO 2, CH 4 (methane), NH 3 (ammonia) Water arose from volcanic activity and icy comets. 200 million years ago - Pangea

Earth’s Shape – Oblate Spheroid Circumference about equator is 43 km larger than the circumference about the poles. 40,075 km at the equator 40,008 km through the poles Highest Point: Mount Everest – 8850 m above sea level. Lowest Point: Mariana Trench – 10,900 m below sea level

Providence, Rhode Island Latitude 41 o 49’ 25’’ N Longitude 71 o 25’ 20’’ W

Equator – 0 o latitude Half way between the two poles One of five primary lines of latitude 40, 075 km (24,901 miles) Sun is directly overhead two days per year Autumnal and Vernal Equinox

Tropic of Capricorn – 23 o S latitude One of 5 primary lines of latitude Sun is directly overhead at N. Hemisphere’s Winter Solstice.

Tropic of Cancer – 23 o N latitude One of 5 primary lines of latitude Sun is directly overhead at N. Hemisphere’s Summer Solstice.

Arctic Circle – 67 o N latitude One of 5 primary lines of latitude Areas above the circle experience polar night (24 hrs without sun above horizon) in winter and polar day (24 hours with sun above horizon) at least one day per year.

Antarctic Circle – 67 o S latitude One of 5 primary lines of latitude Areas below the circle experience polar night (24 hrs without sun above horizon) in winter and polar day (24 hours with sun above horizon) at least one day per year.

Longitude – any point east or west of the Prime Meridian 180 o east to 180 o west Distance varies from 111 km / degree at the equator to 0 km at the poles. Each degree is divided into 60 minutes and each minute divided into 60 seconds.

Prime Meridian – 0 o longitude Established in 1884 in Greenwich, England. The French continued to use the Paris Meridian.

Time Zones of the World 24 zones /360 o = 15 o / time zone

International Date Line – 180 o longitude Opposite Prime Meridian – 0 o longitude Day east of line is one day earlier, day west is one day later, but the same time.

iron (35.0%) - earth’s core oxygen (28.0%) - minerals silicon (17.0%) - minerals magnesium (15.7%) - minerals nickel (1.5%) – earth’s core calcium (1.4%) - minerals aluminium (1.4%) - minerals Composition:

The Atmosphere Three-quarters of the atmosphere's mass is contained within the first 11 km of the planet's surface. 78% nitrogen and 21% oxygen gas (O 2 ) Trace amounts of other gases Argon, carbon dioxide, ozone (O 3 )

Clockwise or Counter-Clockwise??? Does the sun rise in the east or the west?

Providence, RI Latitude: 42 o N Barrow, AK Latitude: 70 o N San Juan, PR Latitude: 18 o N Seasons Around the World