EARTH’S, FORMATION SHAPE, DIMENSIONS AND HEAT CHAPTER 4.1

Earth’s Origin

Observe an animation showing the origin of the solar system.

Earth’s Size and Shape

HISTORICAL EVIDENCE OF SHAPE 1. SHIPS MAST 2. CHANGING POSITIONS OF CONSTELLATIONS 3. EARTHS ARC DURING ECLIPSE 4. GRAVITATION – OBJECTS WEIGH NEARLY THE SAME 5. MAGELLAN’S CIRCUMNAVIGATION

The Earth’s shape is an Oblate Spheroid

OBLATE SPHEROID – TRUE SHAPE OF EARTH. SLIGHTLY FLATTENED AT THE POLES (40,007 KM) BULGING AT THE EQUATOR (40,074 KM). OBJECTS AT THE POLES WEIGH MORE THAN AT THE EQUATOR!

Eratosthenes ( B.C.)

Eratosthenes Greek scholar Greek scholar called the "father of geography“ called the "father of geography“ educated at the academies of Athens educated at the academies of Athens Appointed to run the Great Library at Alexandria in 240. Appointed to run the Great Library at Alexandria in 240. He served as the director of the famous library in Alexandria. He served as the director of the famous library in Alexandria.

ERATOSTHENES – FIRST SCIENTIFIC MEASUREMENT OF THE CIRCUMFERENCE OF THE EARTH. TWO REQUIREMENTS: 1. ANGULAR DIFFERENCE FROM SYENE TO ALEXANDRIA 2. SURFACE DISTANCE BETWEEN TWO CITIES(DIRECTLY NORTH)

Having discovered in his reading that a deep well at Syene (near the Tropic of Cancer and modern Aswan) where sunlight only struck the bottom of the well on the summer solstice, Eratosthenes determined that he could discover the circumference of the earth. Eratosthenes measured the altitude of the noontime sun at Alexandria at its maximum on Jun 21st. Erastosthenes also calculated the tilt of earths axis

Analema a trace of the annual movement of the Sun on the sky a trace of the annual movement of the Sun on the sky Due to the earth's tilt on its axis (23.45°) and its elliptical orbit around the sun, the relative location of the sun above the horizon is not constant from day to day when observed at the same time on each day. Depending on one's geographical latitude, this loop will be inclined at different angles Due to the earth's tilt on its axis (23.45°) and its elliptical orbit around the sun, the relative location of the sun above the horizon is not constant from day to day when observed at the same time on each day. Depending on one's geographical latitude, this loop will be inclined at different angles

Earth is misnamed! Should be called ocean (71%) and land (29%)

Earth’s Interior

Inner core – solid iron and nickle Outer core – liquid iron and nickle Mantle – thickest layer, iron, silicon and magnesium compounds – behaves as a liquid Asthenosphere – slush-like layer of mantle crust floats on Crust – Thin layer of rigid lighter rock that includes earth’s surface Lithosphere – Crust and uppermost part of mantle Layers of Earth

SPECIFIC GRAVITY Weight of an object compared to the weight of an equal volume of water. Useful in mineral identification!

Earth’s avg. density is 5.5 Crust = 2.8

FORMULA S.G = Wa Wa – WH 2 0 Wa = WEIGHT IN AIR WH 2 0 = WEIGHT IN WATER

Earth’s Heat

TEMPERATURE 70 METERS DEPTH CONSTANT AND EQUAL TO AVG. YEARLY TEMP OF THAT LOCATION TEMP IN CRUST RISES 1 0 /40 METERS IN DEPTH 12,800 KM DIAMETER 6400 KM RADIUS X 1000 M/KM DIVIDED BY 40 = 160,000 DEGREES CELSIUS

EARTHQUAKE WAVE STUDIES INDICATE A SOLID CORE, AND THUS THE MAXIMUM TEMPERATURE OF THE CORE WOULD BE C

SOURCES OF INTERNAL HEAT 1.RADIOACTIVITY

2. PRESSURE / COMPRESSION

3. Meteor impacts

Earth’s Magnetic Field

Earth’s Magnetic Field is tilted 11 degrees from the north pole!