Download Shape of the Earth

Mr. Vallee’s
Introduction to Earth
Student Handout
http://www.brainpop.com
http://www.cleanvideosearch.com/media/action/yt/watch?v=B1AXbpYndGc
Big Bang Theory:
Tens of billions of years ago, the universe was incredibly hot and
everything in it was squeezed close together in an area of about 1-2 mm.
Then about 15 billion years ago, the universe began to expand (Big Bang)
and cool. Dust and other particles spread through space (Big Bang process).
Some particles clung together, forming stars, and cluster of stars called
galaxies. Our sun was one such star.
How our Solar System Formed:
About 4700 million years ago (4.7 billion), grains of material from a
rotating cloud of gas and dust consolidated into solid lumps of material.
Through violent collisions with one another, these planetisimals formed
larger bodies, proto-planets. These consolidated further through gravitational
encounters and more collisions. Finally, after no more than 100 million
years, the newborn Sun abruptly brightened, and its radiation blew away any
material that had not been swept up by the planets.
- Heavier rocky silicates condensed closer to the sun
- Lighter material was sent further out by solar wind
http://www.nationalgeographic.com/solarsystem/ax/high.html
- Materials attracted and formed planets
- Other materials continued to bombard Earth, and other planets
How Earth was formed:
- Over time, collisions increased the size of the Earth.
- Then, a larger body collided w/Earth, forming the moon (theory,
composition of moon is similar to the Earth’s crust).
- Heavier materials sunk to the bottom/center of the Earth.
- Lighter materials formed the Earth’s crust.
- Bombardment of asteroids subsided, Earth cooled off, allowing the
condensation of water and the formation of oceans and lakes.
- Gas spewed from volcanoes, made the atmosphere with certain
gases.
Earth’s atmosphere: Consisted of Hydrogen, Oxygen, and CO2, which
together can form amino acids, the building blocks of life. All the above
ingredients allows Earth to harbor life (and not the other planets).
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Earth’s Orbit and its Relationship to the Sun
Length of Earth year: 365.256 days
Ave. distance from the sun 149,600,000 km
Length of day: 23 hours, 56 minutes
Axis tilt: 23.45 degrees (wobbles slightly at its top)
Earth rotates counterclockwise around the sun, and
counterclockwise on its axis.
Earth’s Seasons
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http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level2/activity/song.html
- Earth’s tilt in relation to the sun causes the seasons to change in the
Northern and Southern Hemispheres
- Northern Summer: North pole is tilted toward the sun (Southern
Winter)
- Northern Winter: North pole is tilted away from the sun
(Southern Summer)
- Summer Solstice: (Longer Days) sun reaches the Northernmost
point on June 22
- Winter Solstice: (Shorter days) sun reaches Southernmost point on
December 22.
- Sun crosses the equator 2 times
- Vernal equinox (March 22)
- Autumnal Equinox (September 22)
Causes of Day and Night
- Side facing the sun is daylight, as the Earth rotates the area facing
the sun soon gets less exposure to the sun and nightfall results.
Shape of the Earth
- There is a slight bulge in the middle, as the Earth is thicker through
the middle, than pole to pole. The middle is actually 26.7 miles
thicker in the center.