Formation of the Solar Formation of the Solar SystemSystem

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So, what is the solar system?So, what is the solar system?

The solar system The solar system includes the sun and includes the sun and the bodies revolving the bodies revolving around the sun.around the sun.

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The debateThe debateScientists have long debated Scientists have long debated the origins of the solar system.the origins of the solar system.

In the 1600s and 1700s, In the 1600s and 1700s, scientists that the sun formed scientists that the sun formed first and threw off the materials first and threw off the materials that later formed the planets.that later formed the planets.

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What are planets?What are planets?Before August 2006, there Before August 2006, there was not a scientifically was not a scientifically approved definition of a approved definition of a planet. One definition said planet. One definition said that planets were the nine that planets were the nine major bodies orbiting the major bodies orbiting the sun.sun.

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New Definition…New Definition…The IAU adopted the following definition The IAU adopted the following definition of a planet on August 24, 2006:of a planet on August 24, 2006:– "a celestial body that (a) is in orbit "a celestial body that (a) is in orbit

around the Sun, (b) has sufficient around the Sun, (b) has sufficient mass for its self-gravity to overcome mass for its self-gravity to overcome rigid body forces so that it assumes a rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) hydrostatic equilibrium (nearly round) shape and (c) has cleared the shape and (c) has cleared the neighborhood around its orbit."neighborhood around its orbit."

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New Solar SystemNew Solar System

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Marquis Pierre Simon de LaplaceMarquis Pierre Simon de Laplace

Who was he?Who was he?–A French mathematicianA French mathematicianWhy was he important?Why was he important?–He advanced the He advanced the hypothesis that became hypothesis that became the nebular theory.the nebular theory.

The what?The what?

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What is the nebular theory?What is the nebular theory?

De Laplace’s De Laplace’s hypothesis stated that hypothesis stated that the sun and planets the sun and planets condensed out of the condensed out of the same spinning nebula.same spinning nebula.

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What is a nebula?What is a nebula?

A nebula is a A nebula is a cloud of gas and cloud of gas and dust.dust.

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The rest of the hypothesis…The rest of the hypothesis…

He went on to tell us that the He went on to tell us that the entire solar system formed at entire solar system formed at approximately the same time.approximately the same time.

This hypothesis developed This hypothesis developed into what we now know as into what we now know as the Nebular theory.the Nebular theory.

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The big bang spread The big bang spread matter throughout the matter throughout the expanding universe.expanding universe.

Some of this matter Some of this matter gathered into clouds gathered into clouds of dust and gas.of dust and gas.

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The clouds of gas and The clouds of gas and dust that became our dust that became our solar system was the solar system was the solar nebula.solar nebula.

The solar nebula was The solar nebula was larger than our solar larger than our solar system is now.system is now.

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4 to 5 billion years ago, shock 4 to 5 billion years ago, shock waves from a nearby supernova waves from a nearby supernova or some other force caused a or some other force caused a cloud of dust and gas to contract, cloud of dust and gas to contract, forming the solar nebula.forming the solar nebula.

The sun began to form in the The sun began to form in the center of the solar nebula.center of the solar nebula.

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About 99 percent About 99 percent of the matter in the of the matter in the solar nebula solar nebula became part of the became part of the sun.sun.

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The planetsThe planetsAs the sun was forming, As the sun was forming, planets were forming in the planets were forming in the outer regions of the solar outer regions of the solar nebula.nebula.

The formation of the planets The formation of the planets occurred in stages.occurred in stages.

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What are moons, anyway?What are moons, anyway?

We often hear them We often hear them called satellites.called satellites.

The book defines them The book defines them as the smaller bodies as the smaller bodies that orbit the planets.that orbit the planets.

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http://http://www.cnn.com/TECH/space/9804/21/nasa.planets/planet.formation.38.4.3.mov

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Formation of planetsFormation of planets

The distance between a The distance between a protoplanet and the protoplanet and the developing sun influenced developing sun influenced the composition of the the composition of the planet that formed from the planet that formed from the protoplanet.protoplanet.

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The 4 protoplanets The 4 protoplanets closest to the sun closest to the sun became Mercury, Venus, became Mercury, Venus, Earth and Mars.Earth and Mars.

They contained large They contained large amounts of the heavier amounts of the heavier elements, such as iron.elements, such as iron.

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The next four The next four protoplanets became protoplanets became Jupiter, Saturn, Uranus, Jupiter, Saturn, Uranus, and Neptune.and Neptune.

They formed in the cold They formed in the cold regions of the solar regions of the solar nebula.nebula.

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The material of these The material of these outer protoplanets outer protoplanets was helium, hydrogen, was helium, hydrogen, and frozen gases such and frozen gases such as water, methane, as water, methane, and ammonia.and ammonia.

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They formed into huge They formed into huge planets due to their planets due to their distance from the sun.distance from the sun.

We now refer to them We now refer to them as gas giants.as gas giants.

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PlutoPluto

At the time that our book was At the time that our book was written, Pluto was the farthest written, Pluto was the farthest planet from the sun.planet from the sun.

It was also the smallest of the It was also the smallest of the known planets.known planets.

Pluto is best described as an ice Pluto is best described as an ice ball of frozen gases and rock.ball of frozen gases and rock.

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Dwarf PlanetsDwarf PlanetsPluto is now a dwarf planet.Pluto is now a dwarf planet.According to NASA, a dwarf planet:According to NASA, a dwarf planet:– (a) is in orbit around the Sun, (b) has (a) is in orbit around the Sun, (b) has

sufficient mass for its self-gravity to sufficient mass for its self-gravity to overcome rigid body forces so that it overcome rigid body forces so that it assumes a hydrostatic equilibrium assumes a hydrostatic equilibrium (nearly round) shape, (c) has not (nearly round) shape, (c) has not cleared the neighborhood around its cleared the neighborhood around its orbit, and (d) is not a satellite.orbit, and (d) is not a satellite.