formation of the Universe [appearing pictures with notes] [2]

• Most astronomers think that the Universe was formed during an event called the Big Bang.
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• This was a giant explosion which occurred between 10 and 20 billion years ago.
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• During this, all of the space, time, matter, and energy in the Universe was created.
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• The explosion hurled matter in all directions and caused space itself to expand.
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• As the Universe cooled, the material in it began to combine.
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• Every object has gravity and creates a "gravitational" pull on those objects around them.
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• The gravitational pull of some of the larger objects pulled more and more material in.
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• Some of them grew big enough for their gravity to shape them into spheres.........
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• .... and some of these clumps smashed into one another, forming larger and larger objects.
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• As the Universe cooled, the material in it combined to form galaxies, .........
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• .............stars, like our Sun,
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• and planets, like the Earth.
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• Our Solar System is located in an outer spiral arm of the Milky Way galaxy.
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• It was formed about 4.5 billion years ago.
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• Our Solar System consists of our star, the Sun............
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• ... the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune,
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• ............and dwarf planets such as Pluto.
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• A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun.
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• ....dozens of moons around hundreds of planets.
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• ....and millions of asteroids, comets and meteoroids.
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• What is an asteroid?
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• What's the difference between meteoroids, meteors, meteorites, comets and asteroids?
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