Earth’s Spheres Atmosphere: the envelope of gases that surrounds the Earth. Earth’s Spheres Hydrosphere: water part of the Earth, including surface and subsurface water. Hydrosphere Refers to the watery part of the Earth. Most of the Earth’s water is in oceans but also in lakes, streams rivers, groundwater and glaciers. Hydrosphere 97% is salt water The remaining 3% is fresh water, 2/3 of the total freshwater is frozen in the ice caps of the North and South Poles. Hydrosphere The hydrosphere also includes water found in the atmosphere and the amount tied up in the cycle. Earth’s Spheres Biosphere-Includes things on Earth all living Earth’s Spheres Lithosphere: outer solid shell of the Earth that extends 70 km or more from the crust and part of the Asthenoshere Lithosphere Includes the earth’s crust and the upper mantle. It is 100 km thick The lithosphere is broken up into plates. They can move around independently of each other. The plates float around on the asthenosphere, the liquid portion of the mantle. Earth’s Spheres Asthenosphere: partially melted layer of mantle below the lithosphere. This is responsible for plate tectonic movement. 1. Crust: 10-65km thick A) Thickest under the continents. B) Low density. C) Lighter rock. D) Solid. 2. Mantle: The upper mantle contains magnesium, silicon, and iron. A) 2900km ~ the thickest layer. B) Made up of heavier rocks. C) The upper mantle contains the Asthenoshere which is soft and flowing. 3. Outer Core: the base of the mantle A) Liquid iron and nickel. B) 2175 km 4. Inner Core: solid iron and nickel. A) Spherical in shape. B) 2575 km in diameter. Atmosphere The gaseous layer, extending from the surface of the earth to outer space. It is made up of a mixture of gases with some suspended solids and liquids. The most common gases are Nitrogen 78% Oxygen 21% 1% water vapor and others - The earth was NOT structured like this 4 billion years ago. - According to the Protoplanet Hypothesis, the surface of the earth looked like the moon does. - The rock throughout the earth was same all the way through. - As the earth heated, iron and nickel melted, flowed downward toward the center. On the way it melted lighter materials and forced them upward to the surface. - The lighter rock became solid and formed the crust. Layers of the Atmosphere The atmosphere filters ultraviolet rays and protects living things from the sun’s harmful UV rays. 5 Layers of the Atmosphere The layers become less dense (thick), the farther away from the Earth’s surface you go. Troposphere Troposphere – surface to 10 km (~6 miles) above. Contains most of the gases The air we breathe is here Most weather occurs here. 1. Stratosphere Stratosphere – 10km-45km (6-28 miles) above The air is very thin here, but wind still blows. Airplanes fly in the lowest parts Contains the ozone layer, which protects us from the Sun’s UV rays. 2. Merge with Outer Space 3. Mesosphere 4. Thermosphere 5. Exosphere “It’s often said that you cannot get something for nothing, but the universe may be the ultimate free lunch.” Alan Guth---physicist How did the Earth Begin? meteroids,asteroids,comets No scientist knows for certain how Earth was formed or from what it came. There are a number of theories on the origin of earth. All of these theories must consider the following scientific facts: How did the Earth Begin? A. All planets revolve around the sun in the same direction (counter clockwise) B. The paths or orbits of planets are all nearly circular. C. Orbits of planets are in nearly the same plane. D. The sun rotates on its axis in almost the same plane as the planets How did Earth Begin? E. Most planets rotate in the same direction as the sun. F. 6 planets have moons and most revolve around the planet as the planet does the sun. G. The sun’s rate of rotation is slower than expected by scientists. The Big 3 1. ENCOUNTER HYPOTHESIS The Solar system began approximately 5 billion years ago with our sun already in existence. The sun is hanging out when a star or perhaps a comet passes very close to the sun. ENCOUNTER HYPOTHESIS A collision happens and HUGE amounts of gas from the sun explode out of it but move in the same direction around the sun. After a million years, the gases shrink into ball shaped bodies. The larger ones become planets and the smaller ones become moons. The ones that never shrank became comets. NEBULAR HYPOTHESIS A HUGE cloud of gas rotates through space, this cloud is called a nebular. The nebula cools and shrinks, making it spin faster. The spinning increases causing it to throw off a ring, then another until it has thrown off nine rings. Each thrown ring becomes a planet. NEBULAR HYPOTHESIS The cloud at the center shrinks A LOT more. The shrinking causes compression which causes heating and it becomes a fiery HOT star. The sun, planets and moons are all spinning in the same direction as the original nebula that they came from. PROTOPLANET HYPOTHESIS This is the theory most in favor right now. The solar system began with a great cloud of gas and dust. The cloud shrinks under the pull of its own gravitational force. The material concentrates in the center where compression causes it to get really hot and it forms the sun. PROTOPLANET HYPOTHESIS Unlike the Nebular hypothesis, there are no rings. 10% of the cloud’s matter forms a single disk around the sun. Both the disk and the sun rotate slowly. PROTOPLANET HYPOTHESIS Gravity within the disk causes material to collect in several huge whirlpools called eddies. Write this on bottom of notes! Eddies_beginning of sun formationplanetesimalsprotoplanetssun ignitesplanets and moons There are some leftoverscomets, meteors asteroids, planetoids(large asteroids) Link How does the Earth evolve over time? There are 3 theories on the evolution of the universe: 1. The Big Bang Theory Proposed by Le Maitre and Gamnlow In the beginning… All matter in the universe was concentrated in an EXTREMELY dense and hot fireball. 20 billion years ago: a HUGE explosion occurred The Big Bang Theory All that matter was broken into pieces and thrown with high speed in all directions. Eventually this formed stars and galaxies and these bodies are STILL moving away from each other. As the matter cooled from the explosion, Hydrogen and Helium gas formed. 1 billion years later, the first stars were born. 2. Steady State Theory Proposed by Bondi, Gold and Hoyle The theory: The number of galaxies in the universe is constant and new galaxies are continuously created out of empty space when galaxies leave our universe. The mass of the universe remains the same. 3. Pulsating Theory The universe is supposed to be expanding and contracting alternately…in other words pulsating Right now it’s expanding. The expansion is stopped by the pull of gravity and begins to contract again. Once it reaches a certain size, an explosion would occur and the universe starts to expand again.