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UNIT 3: FORMATION OF THE SOLAR SYSTEM Mrs. Boorom The sun and all the planets and other bodies that revolve around it make up the solar system. Planets are the primary bodies that orbit the sun. In the 1600s and 1700s, many scientists thought that the sun formed first and threw off the materials that later formed the planets. However, in 1796, Pierre-Simon LaPlace advanced a hypothesis called the Nebular Hypothesis. Laplace’s hypothesis states that the sun and the planets condensed at about the same time out of a rotating cloud of gas and dust called a nebula. Modern scientific calculations support this hypothesis. THE NEBULAR HYPOTHESIS: Matter in the universe is gathered in clouds of dust and gas. 5 billion years ago, gravity increased greatly and this rotating cloud of dust and gas formed the sun and planets. This cloud that formed the planets is called a solar nebula. The inside of this cloud became extremely hot (10,000,000 oC)from collisions and pressure at the center of the solar nebula. At this temperature, hydrogen fusion began and the sun was formed. About 99% of the matter of the solar nebula makes up the sun Small bodies from which a planet originated in the early development of the solar system are called planetesimals. Some planetesimals joined together through collisions and through the force of gravity to form larger bodies called protoplanets. Moons are the smaller bodies that orbit the planets. Protoplanets not massive enough to clear away other objects near their orbits became the dwarf planets. FORMATION OF THE MOON… A COLLISION WITH A MARS LIKE PROTOPLANET AND EARTLY EARTH. SOURCE; NASA INNER PLANETS: Mercury Venus Earth Mars INNER PLANETS Close to the sun Contain large percent of heavy elements, such as iron and nickel. The denser materials sank to the center of planets thus forming layers. The inner planets are smaller, rockier, and denser than the outer planets. OUTER PLANETS Jupiter Saturn Uranus Neptune Formed in the colder region Did not lose their lighter elements, such as hydrogen and helium ;or ice Thus Jupiter and Saturn are called gas giants; while Uranus and Neptune are the ice giants. PLUTO: THE FIRST DWARF PLANET (SINCE 2006) Originally the 9th planet and named in 1930 Smaller than Earth’s moon Made of frozen gas and rock Its orbit is very tilted. Your turn… On ISN page 18, use color pencils to copy FIGURE 2 on page 750-751. Then add your own VISUAL VOCAB or a CONCEPT MAP of the key words from today’s lesson. *IF not finished in class, finish for HW! On ISN page 18, use color pencils to copy FIGURE 2 on page 750-751. Then add your own VISUAL VOCAB of the key words from today’s lesson. *IF not finished in class, finish for HW! ` On ISN page 18, use color pencils to copy FIGURE 2 on page 750-751. Then add your own VISUAL VOCAB of the key words from today’s lesson. *IF not finished in class, finish for HW! On ISN page 18, use color pencils to copy FIGURE 2 on page 750-751. Then add your own VISUAL VOCAB of the key words from today’s lesson. *IF not finished in class, finish for HW! On ISN page 18, use color pencils to copy FIGURE 2 on page 750-751. Then add your own VISUAL VOCAB of the key words from today’s lesson. *IF not finished in class, finish for HW! FORMATION OF SOLID EARTH When Earth formed, its high temperature were due to: Energy from collisions, compression of outer layers, and radioactive materials. Dense materials, such as molten iron, sank to Earth’s center. Less dense materials were forced to Earth’s outer layers in a process called differentiation. This caused Earth to form three distinct layers. EARTH’S 3 LAYERS At the center is a dense core composed of iron and nickel. In the middle is the mantle composed of iron and magnesium rich rock. The outermost layer is the crust composed of silica-rich rock and is least dense. Earth’s surface continued to change as a result of heat transfer. The original atmosphere of Earth consisted of hydrogen and helium. The sun heated these gases so they escaped Earth’s gravity. Earth’s early atmosphere continued to form when volcanic eruptions released gases in a process called outgassing. These volcanic eruptions occurred more frequently than today. Volcanoes released the following gases: water vapor, carbon dioxide, nitrogen, methane, sulfur dioxide, and ammonia. The molecule that contains three oxygen atoms and collects in Earth’s upper atmosphere is called ozone. It shields Earth’s surface from the harmful UV (ultraviolet) radiation of the sun. EARTH’S PRESENT ATMOSPHERE Some of Earth’s early organisms, such as cyanobacteria and early green plants, used carbon dioxide during photosynthesis. Oxygen: is a byproduct of photosynthesis and was released into the atmosphere. About 2 billion years ago, oxygen increased greatly in the atmosphere. It is similar to the amount found in the atmosphere today. FORMATION OF EARTH’S OCEANS Comet collisions may have contributed a significant amount of water to Earth’s surface. Earth’s first oceans were made of fresh water. Over millions of years and rain water traveling through rivers to reach the ocean created salt water from dissolved rocks on land. Earth’s atmosphere and surface cooled because ocean water dissolved much of the carbon dioxide in the atmosphere.