Transcript Light Years and Our Universe

Light Years and Our
Universe
STAAR 2012- 8th Grade
How far is far? (think of
the furthest place)
How fast is fast? (think of
the fastest you can travel?
How do they measure that far?
Year – the distance that
light travels in 1 year which is
equal to 9.46 trillion kilometers
(in a vacuum)
 The symbol for light year is
“ly”.
 Light
 So,
if Jupiter is 620 million
kilometers away from Earth can light
get from here to Jupiter in less than
a year?

Yes it can
 Monoceros
Nebula is 1000 trillion
kilometers from Earth. How many
light years is this?

Approximately 106
 How
many seconds are in
a year?

31,557,600 s/yr
c
= 299,792,458 meters
per second
 or 186,000 miles per
second
The Speed of Light
One
light year is approximately
5.880 trillion miles (mi).
Light
travels 9.46 trillion
kilometers (km) a year.

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Light years are used to
measure the vast distances
in space.
In the universe, the kilometer
measure is too small to use.

Every time you look at
objects in the night sky or
the Sun, the light from
that object is old. You are
looking at history.

It takes 8 light minutes for
light leaving the Sun to reach
the Earth.

To put this in perspective, if you
could drive from the surface of the
Sun to the surface of the Earth, it
would take you 180 years driving
nonstop at 60 mph.
Sirius, in the constellation Canis
Major, is the sky’s brightest star. It is easy
to find on winter and spring evenings.
 When you look at Sirius, you are
looking back in time to see how Sirius
looked 8 years ago. The light left the star 8
years ago.
 So how many light years away is Sirius?
 8 ly

Big Bang Theory (not the t.v. show)

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A theory that the universe started from a
single atom!
Georges Lemaitre – First suggested the
“Big Bang Theory”
This theory was made because scientist
discovered that other galaxies are moving
away from ours at a great speed (the
universe is expanding)
Big Bang Theory

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With the Big Bang, space itself began expanding
like the surface of an inflating balloon and all the
matter moved along with it.
The Big Bang is NOT like an explosion of matter,
in otherwise empty space. Space itself began with
the Big Bang and carried matter with it as it
expanded.
There was no explosion! there was, and continues
to be, an expansion. It was an EXPANSION.
The Big Bang
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Scientist think that all matter was tightly
compressed or squeezed into a hot, dense
ball a few millimeters across.
After the Big Bang the universe has
continued to expand and as matter cooled
more atoms developed as did galaxies and
stars
Big Bang Evidence: what scientist use
1.
2.
3.
4.
The universe has to have a beginning
The galaxies are still moving away from each
other (suggest that the universe was once much
smaller)
If the universe was once hot there should be
proof, and scientist found cosmic radiation
readings that showed this.
The abundance of “light elements” such as
helium and hydrogen.
Big Bang Scientist
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Albert Einstein – added to the Big Bang
Theory with his own theory of relativity.
Edwin Hubble – Discovered that the
galaxies are moving away from our own at
a great speed. (Hubble Law)
Arno Penzias and Robert Wilson –
discovered cosmic radiation