Ch 2 Earth’s Size & Shape

I. Model A representation of an object, a process, or a phenomenon. Ex. Globe – best, most to scale model of the Earth Computer Climate models/Simulations

II. A System Part of the Universe that can be studied separately Closed System- a system in which energy can enter or leave, but matter cannot Open System- a system in which there is a free exchange of both energy & matter between the system & its surroundings.

III. Structure of the Earth Inner Core - layer of the Earth composed of solid iron & nickel Outer Core - layer of the Earth composed of liquid iron & nickel

Structure of the Earth Cont’ Mantle - largest Earth layer composed of silicon, oxygen, magnesium, & iron Crust - outer most layer of Earth the deepest mines & caves go no further than the crust thicker under the continents than the ocean

Layers of the Earth

IV.Temperatures Below the Surface Deep caves stay about the same temperature all year From 0 m to 20 m below, a cave usually remains equal to the avg. yearly temperature Every 40 m below the 1st 20 m, the temperature in a cave 10C for each 40 m (120ft)

Heat is from: Radioactive Minerals Ex Uranium & Thorium Compression of the crust by gravity

V. Earth’s Shape Evidence that Earth is Spherical The mast of a ship is the 1st part to appear over the horizon & the last to disappear.

Earth From Space Photographs of Earth from space

An eclipse of the moon occurs when Earth's shadow falls on the moon Earth’s Shape Cont’ An eclipse of the moon occurs when Earth's shadow falls on the moon The shadow is always an arc of a circle http://www.rit.edu/~andpph/eclipse-01-20-00.htm l

Earth’s Shape Cont’ Ships sailing north or south observed changes in the nighttime sky. North Star appears higher in the sky as a ship travels north Ships sailing south lose sight of the Big Dipper & begin to see the Southern Cross

B. Oblate Spheroid Sphere that is slightly flattened at the poles & bulged at the equator Caused by Earth's rotation

C. Weight on Earth

VI. Earth’s Density Density – The amount of matter (mass) in a given space (volume) Average density = 5.5 g/cm3

VII. Measuring Earth's Circumference Eratosthenes (er uh Tos thuh neez) Of Greek heritage, born in Cyrene, now Shah hat, (Libya) Studied at Alexandria & Athens Appointed Director of the Alexandrian Library, 236 BC

Eratosthenes Cont’ Lived in Egypt 1st Scientific Measurement of Earth’s Circumference Went blind 195 BC Starved himself to death 194 BC

Facts Eratosthenes knew: At noon on June 21st (Summer solstice): The sun casts a shadow of 7.2o from an obelisk in Alexandria The sun cast no shadow in a well in Syene (called Aswan today)

Facts Eratosthenes knew: Believed the suns rays hit the Earth as parallel lines Eratosthenes figured Syene was due south of Alexandria (He was slightly off on this one) Distance between Syene & Alexandria (925km) slightly off Thought both cities were on the same line of longitude (off on this by 30)

VIII. Types of Data Qualitative – data that is relative but not numeric. Ex. The color of an object or stating someone is tall or taller than another person Quantitative – data where a numeric measurement or a count of objects has been made

IX. 4 Spheres/Subdivisions of Earth Atmosphere Geosphere Hydrosphere Biosphere

1. Atmosphere Atmos- Greek, Meaning vapor Ozone- O3, protects Earth from Sun’s harmful UV rays Oxygen & Carbon Dioxide provided for living things Water vapor forms clouds

2. Geosphere Geo –Greek, meaning Earth Rocks, Mountains, Beaches

3. Hydrosphere Hydro- Greek meaning water All the water of the Earth’s System Oceans Glaciers Groundwater Rivers Lakes

4. Biosphere Bio- Greek meaning Life All forms of life on Earth from microscopic to Human