Chapter 2-1 Earth

Age of Earth 4.6 billion years old Oldest rock: 3.8-3.9 billion yrs old

The “watery planet” 70 % surface covered with water 97 % salt water 3 % fresh water

Earth’s Shape:

Oblate Spheroid: What causes this shape? Bigger at the equator Polar circumference: 40,007 km Equatorial circumference: 40,072 km What causes this shape?

Atmospheric Composition Nitrogen (N2) = 78.08 % Oxygen (O2) = 20.95 % Water (H2O) = 0 to 4% (variable) Argon (Ar) = 0.93 % Other gases

Role in space 3rd planet from the sun One satellite = moon How does everything stay in orbit?

Gravity the attraction between objects Newton’s Law of Gravity

Newton’s Law of Gravity Any two objects attract each other More massive object, stronger the attraction Closer two objects are, stronger attraction End day 1

Earth’s Interior continued… How do scientist know so much about the composition and location of each layer found in Earth?

Seismology Study waves that are given off when an earthquake occurs.

Primary (P) and Secondary (S) Waves P waves: Move twice as fast as S waves Move through rock or liquid S waves: Move only through rock Change behavior according to material they pass through

Crust: Accessible – top layer Thinner under oceans than continents

Boundary between crust and mantle Moho (Mohorovicic) Detected by sharp increase speed of earthquake waves Increase because of change in rock type

Mantle: Divided into three parts Lithosphere: solid part of Earth, crust and upper mantle Asthenosphere: temp. of rock near melting pt. Mesosphere: solid, molten rock

Asthenosphere 200-250 km below Earth’s surface Temperature of rock near melting point Molten rock from volcanoes “Plastic” layer - rock flows very slowly

Core Outer core: Liquid because S waves don’t pass through iron Creates Earth’s magnetic field

Earth’s Magnet Causes: Magnetosphere 1. Liquid Iron Core. 2. sun’s magnetic field 3. moon’s magnetic field Magnetosphere

Inner Core Inner Core: End day 2 Mostly iron 9032-10832 degrees F High pressure = solid Doesn’t spin because solid End day 2

Earth’s Gravity (day 3) Newton’s Law of Gravity: force of attraction depends on what two things?

Weight Depends on: measure of the pull of gravity on an object 1. Mass 2. distance from Earth’s center measure of the pull of gravity on an object Unit = Newton (N) 1 kg of mass (on Earth)= 10 N

Weight changes with location 100 pounds on Earth = Moon – 17 pounds Jupiter – 254 pounds Sun – 2790 pounds

Mass Amount of matter something contains Grams Stays constant end