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The Discovery of Universe
By:
Karen
Ivy
Introduction Of Edwin Hubble
 Edwin Powell Hubble (November 20, 1889 – September 28,
1953) was an American astronomer.
 His keen knowledge was combined with a powerful toolHooker Telescope with its 100-inch mirror on top of Mount
Wilson in California. Hubble used the telescope resolution
and light gathering power to take a series of photograph of
the great nebula in Andromeda. An nebula is an interstellar
cloud of dust, hydrogen, helium and other ionized gases
and Andromeda is a spiral galaxy. For the first time the
image revealed faint stars in the nebula. Hubble now knew
the Andromeda was a collection of stars.
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Discovery Of Galaxy
 Hubble had a question: How far away is the Andromeda
Nebula?
 He calculated the distance based on the variable stars. In
1923, Hubble found dozens of these variable stars in
Andromeda, and determined their distance. Andromeda
contains a spiral-shaped galaxy that, at a distance of 2.2
million light-years, is the farthest object visible to the
naked eye. He calculated that Andromeda must be at least
10 times farther away than the farthest stars in the Milky
Way. The Andromeda nebula was really the Andromeda
galaxy. This discovery implies that the other, even fainter,
spirals were probably also galaxies even farther away. A
nebula is an interstellar cloud of dust, hydrogen, helium
and other ionized gases. Astronomers no longer thought
our galaxy was the entire universe. Now they knew that the
universe was composed of many, many galaxies.
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The Big Bang Theory(1)
 How did our universe begin? How old is our universe? How
did it all begin? Everyone was curious about this question.
 Many once believed that the universe had no beginning or
end and the universe was infinite. Through the inception of
the Big Bang theory, the universe was no longer considered
as infinite. The origin of the Big Bang theory can be
credited to Edwin Hubble. Hubble made the observation
that the universe is continuously expanding. He discovered
that a galaxy’s velocity is proportional to its distance.
Galaxies that are twice as far from us move twice as fast.
The Big Bang Theory(2)
 Universe is expanding in every direction. This observation
means that it has taken every galaxy the same amount of
time to move from a same starting position to its current
position. Just like the Big Bang provided for the beginning
of the universe, Hubble's observations provided for the
beginning of the Big Bang theory. Since the Big Bang, the
universe has been continuously expanding and, thus, there
has been more and more distance between clusters of
galaxies. Galaxies moving farther away from each other is
known as the red shift. As light from distant galaxies
approach earth there is an increase of space between earth
and the galaxy, which makes wavelengths being stretched.
The Big Bang Theory (3)
 The universe began in an extremely hot and dense
condition and it was continuously expanding, even
today. But the universe is getting cooler as well,
scientists believe that universe was approximately
13.8 billion years ago. Scientists base the Big Bang
theory on many different observations. The most
important is the red shift of very far away galaxies.
Red shift is the Doppler Effect occurring in light.
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Red Shift
 In physics, redshift happens when light or other
electromagnetic radiation from an object moving away
from the observer is increased in wavelength, or shifted to
the red end of the spectrum. In general, whether or not the
radiation is within the visible spectrum, "redder" means an
increase in wavelength – equivalent to a lower frequency
and a lower photon energy, in accordance with, respectively,
the wave and quantum theories of light.
 This is an example of
red shift. On the left is
a ray of light from the
Sun, and on the right
one from a far off
galaxy. As you can see,
all the lines shift
towards the red end of
the spectrum due to
red shift.
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 Something similar happens to sound waves when a source
of sound moves relative to an observer. This is called the
Doppler effect.
 As the train moves towards a person, the sound it makes as
it comes towards them sounds like it has a higher tone,
since the frequency of the sound is squeezed together a little
bit. As the train speeds away, the sound gets stretched out,
and sounds lower in tone. The same happens with light
when an object that emits light moves very fast. An object,
like a star or a galaxy that is far away and moving toward
us, will look more blue than it normally does. This is called
blue shift. A star or galaxy moving farther away from us will
look more red than it should, that's where red shift got its
name.
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Thanks
For
Watching!
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