The Expanding Universe

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21-5: The Expanding Universe:

21-5: The Expanding Universe

The Expanding Universe:

The Expanding Universe So how do we explain the awesome vastness of everything we see in space? Beyond the Big Bang 4:25-8:15

The Expanding Universe:

The Expanding Universe A man named Edwin Hubble was the first to group and name galaxies. He also realized that almost all galaxies (except for a few neighboring galaxies) seemed to be moving apart . He realized that the universe was expanding ! Note: The expanding universe applies to all objects that are not bound together by gravity . For example: Gravity is pulling our neighboring galaxy, Andromeda, toward the Milky Way and may be on a collision course with the Milky Way! (3 or 4 billion years)

PowerPoint Presentation:

The expanding universe can be explained by comparing sound waves with light, which follow the same rules . The pitch of sound changes with the distance to the listener - The Doppler effect. As the sound travels away from the listener, the deeper the sound (longer wavelength) ...and the reverse is true when the sound approaches the listener (shorter wavelength) The Expanding Universe

PowerPoint Presentation:

This can be applied to astronomy, matter moving away from us seems reddish (longer wavelength), and the opposite to objects approaching us, more bluish (shorter wavelength). Spectral lines are shifted toward the red end of the spectrum when objects move away- “Red Shift” The Expanding Universe

In 1924 Edwin Hubble first measured a “Red Shift” of the galaxies which led him to conclude that the Universe is expanding! :

In 1924 Edwin Hubble first measured a “Red Shift” of the galaxies which led him to conclude that the Universe is expanding ! The Expanding Universe Also, he noticed the farther are they are apart, the faster they are moving apart! This became known as Hubble’s Law – the farther away a galaxy, the faster it is moving away.

PowerPoint Presentation:

The galaxies in the universe are like the raisins in rising bread dough. The move apart from each other in all directions. Imagine you were a raisin. The farther apart a raisin was from you, the faster it would move away from you because there is more bread dough to expand between you and the raisin. The Expanding Universe

The Big Bang Theory:

The Big Bang Theory Most galaxies are moving rapidly away from our galaxy and from each other. This means they must have once been together? The Big Bang Theory- States that the universe was incredibly hot and dense and only the size of the period at the end of this sentence. According to the Big Bang Theory, the universe formed in an instant , billions of years ago, in an enormous explosion . By studying the speed of the moving galaxies, scientists believe that the universe has been expanding for 13.7 billion years , in other words that is the approximate age of the Universe! The Big Bang!

Formation of the Solar System:

Formation of the Solar System Our solar system consists of our sun and planets. After the big bang, matter in the universe collected together forming galaxies. Gas and dust in a galaxy formed stars . Our Sun was likely born 5 Billion Years ago. After the formation of the sun, left over gas and dust formed planetesimals ;small pre planets which collided and grew into larger planets.

Formation of the Solar System:

The inner planets are “rocky” or “terrestrial” because they formed close to the sun and particles from the sun, the “solar wind”, blew the gases away. (Mercury, Venus, Earth, Mars) The outer planets that formed far from the sun are “gas giants” and may have a rocky core but have no solid surface (Jupiter, Saturn, Uranus, and Neptune). The solar wind blew the gases to these “gas giants”. Formation of the Solar System

The Fate of the Universe:

The Fate of the Universe It seems that the Universe is now expanding faster and faster. The current consensus is that the Universe will probably continue to expand forever . If this happens all of the stars will eventually run out of fuel and the universe will be cold and dark. Astronomers are not sure of the force that is causing the expansion of Universe to speed up but for now they are calling it Dark Energy . There are still many puzzles to be solved!

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