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Space Science
Chapter 16
1
•Universe
–everything physical that
exists in space.
•Galaxy
–Collection of stars
bound together by
gravity.
2
•Light Year (ly)
–Distance that light
travels in one year.
–Speed of light (c)
3.0 x 108 m/s
–9.5 x 1015m/yr
3
•Did you know…the light you
see from the sun actually left
the sun 8 minutes earlier!?!
•Nearest stars other than the
sun are 4.3ly away (6.09 x
1016m)! What are they???
•What does that mean about
the light you see from them?
4
The nearest galaxy to our own is
more than 2 million light years
away from our galaxy.
What is the name of our galaxy?
5
Galaxies & Gravity
• Gravity draws clouds of dust together to
form stars.
• Gravity draws stars, dust, and gas into
larger units that we call galaxies.
• Gravity also causes galaxies to cluster
together.
• Superclusters are large groups of
galaxies drawn by gravity
6
• Our solar system is inside of
the Milky Way Galaxy.
• The galaxy contains clouds of gas
and dust (interstellar matter).
• The galaxy has a bulge in the
middle. Why???
7
• There are 3 types of galaxies
• Types are based on the shapes
of the galaxies
1) Spiral
2) Elliptical
3) Irregular
8
Spiral Galaxies
•Often have spiral arms
that contain material for
forming new stars.
•Blue tint is due to the blue
color of newly forming
stars.
•Blue is most notable in the
arms.
9
• Older than spiral galaxies
• Stars are older and no spiral
arms.
• Older stars are redder in color.
• Elliptical galaxies vary greatly in
size.
10
• Some contain very little gas or
dust particles.
• Some are clouds of matter that
never gave rise to stars.
11
So, how
did it all
begin???
12
The Big Bang Theory
•If the universe is constantly
expanding outward, then to
go back in time would bring all
matter to one point of origin.
•This would look like a giant explosion.
•According to this theory the explosion
released all of the matter and energy
that exists in the universe today.
13
Is there support for the
Big Bang Theory??
• In 1965 cosmic background radiation
was discovered. It is thought that this is
the remains of the energy of the big bang.
• The presence of these waves
was predicted in the Big Bang
Theory.
• The red shift also supports the
theory.
14
• Hubble’s Red Shift theory.
• Stars emit a pattern of spectral lines.
• Stars from other galaxies show the pattern
shifted to the red end of the spectrum.
15
Red Shift & Blue Shift
16
Where is the Universe headed?
•The universe is expanding, but at
what rate?
•Is it happening faster or is it slowing
down?
•The 3 possible results depend on how
much matter there is in the universe.
1)Expand forever
2)Slow but never stop growing
3)Collapse back into itself
17
• The Sun is an average star.
• The sun is much larger than
the Earth (about 110 times the size)
• The mass of the sun is 300,000 times the
mass of Earth.
18
•Depends upon the temperature, size,
and distance from Earth.
•Stars don’t just produce energy in the
form of light.
•They also produce High frequency x-rays
and low frequency radio waves.
19
Temperature and color of stars
• Hotter objects glow with light of higher
intensity at shorter wavelength. This light
is more toward the blue or violet end of the
visible light spectrum.
• Cooler objects glow with light intensity at
the longer wavelengths or more toward the
red end of the spectrum.
Spectral Lines and composition
20
Nuclear Fusion and Stars
•Stars are massive balls of
hydrogen and helium.
•They are held together by the
gravity caused by their own mass.
•Extremely high pressure and
temperature result in nuclear fusion.
•This in turn releases energy
outward.
21
Life of a Star
• Stars have a life cycle just like
other things in nature.
• A beginning, a middle, and eventually an
end.
• The beginning is a nebula, or cloud of gas
and dust that start to collapse inward due
to gravity.
22
• The cloud of gas begins to
collapse due to its own gravity.
• As it collapses the cloud
begins to spin.
• As the cloud gets smaller it
spins faster.
• The center reaches high
temperatures and pressures
and the electrons are driven off
of hydrogen.
• Nuclear fusion begins and a
star is born.
• Fusion reactions produce an
outward force.
23
Balance of forces in a Star
•The inward force of
gravitational pull is balanced
with the outward force of the
energy of nuclear fusion in the
center of the sun.
•Estimates are that this balance
of forces on the Sun has
existed for 5 billion years and
should continue for another 5
billion years.
24
•
•
•
•
Life cycle of the Sun
When fusion of hydrogen slows the
center of the sun will contract while the
outer layers expand.
The sun will then be a red giant.
When the red giant begins to reach the
end of its course it will become a
white dwarf.
When it cools completely it will become
a brown dwarf.
25
26
Stars larger than the sun
•These stars (1.4 times larger than the
sun) become Supergiants.
•Due to the mass of these stars fusion
stops, resulting in a massive explosion
known as a supernova.
•After a supernova the star will
become either a neutron star or a
black hole depending upon its mass.
27
28
• “Eight planets” orbit the sun(Copernicus)
• The planets are:
Mercury, Venus, Earth, Mars,(Ceres) Jupiter, Saturn,
Uranus, Neptune, (Pluto), (Charon, and 2003 UB 313)
• Planets move in elliptical orbits (Kepler)
• They are visible due to the ability to reflect light.
29
•
•
•
•
•
•
•
•
My
Very
Excellent
Mother
Just
Served
Us
Noodles
30
Pluto is no longer a planet! The giant asteroid
Ceres, Pluto's moon Charon, and a large
outer-solar system object called 2003 UB313
fall into the same category as Pluto (Dwarf Planets)31
• These planets are relatively small and
have rocky surfaces.
• Why are they called the inner planets?
They are
located inside
the asteroid belt.
32
• Larger than inner planets and composed
of large gas clouds.
• They are called the gas giants.
Jupiter
What is the largest
planet?
33
34
• 385,000 km from Earth.
• Covered with craters
(caused by what?)
• Phases of the moon
–What are they?
–What causes the
phases of the moon?
The relative positions of Earth,
Sun, and the Moon
35
36
• Solar eclipse
– When the moon blocks
out the suns rays.
37
Lunar eclipse
When a full moon has the suns
rays blocked by the Earth.
38
Summer and Winter Solstice
• In the Northern
Hemisphere winter
solstice is the shortest
day of the year.
• In the Northern
Hemisphere summer
solstice is the longest
day of the year.
• What about the southern
hemisphere?
June 21 or 22
December 21 or 22
39
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