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Origins of the Universe
and Solar System
From Universe to Galaxy to Solar System
Two Observations about the Universe Led to the Big Bang Theory
In 1965, scientists Penzias And Wilson
discovered background radiation
interfering with radio antennae, causing a
hiss in phone lines.
II. Evidence for Big Bang/Inflation
• That radiation is called cosmic background
radiation and is thought to be radiation from
the big bang.
• This radiation can be detected by common
radio and television antennae. (ex: “snow”
on an old television is made up of a small
percent of radiation from the formation of the
universe!)
II. Evidence for Big Bang/Inflation
2. Astronomers
observe “red shifts” of
starlight throughout the universe.
• This redness is the result of light waves
being stretched as objects in the universe
move away from each other (the result of
the big bang).
What is Doppler Effect?
Doppler Effect is the
change in frequency of
a wave (such as a
sound wave) when it is
observed relative to a
moving source (like a
car)
Light waves can also experience Doppler Effect when
the source of the light (such as a star) is moving
Astronomers observed that light from distant stars has been
shifted towards the red end of the light spectrum.
This phenomenon is called red
shift.
The farther away a star is, the more its light is shifted
towards the red end of the spectrum, demonstrating that
the universe is expanding….
I. Formation of the Universe
The Big Bang Theory - The theory that the
universe began as a point(singularity) and
has been expanding ever since.
•  The universe was originally packed into
one dense sphere of hydrogen about the
size of a pearl!
I. Formation of the Universe
The Big Bang Theory - The theory that the universe began
as a point(singularity) and has been expanding ever
since.
•  The sphere “exploded”, forming a hot
expanding cloud
•  As the cloud moved, parts condensed
and formed billions of galaxies
I. Formation of the Universe
The Big Bang Theory -.
•  The galaxies continue to move
outward today
•  Most commonly accepted theory of
universe formation
Theories on the Formation of the Universe Continued.
B.  The Steady State Theory - The belief that the universe doesn’t change
with time but more matter is added to the universe as it expands.
•  Popular during the 1950s and 1960s
•  The universe had no beginning and has no end (no big bang)
C.  Inflationary Theory - predicts that there was a sudden expansion
when the universe was very young, more extreme than predicted by
the big bang theory!
•  Considered to be a “revised” Big Bang theory
•  The universe expanded and cooled until about 10-35 second after
the big bang when it became so cool that the forces of nature
caused the universe to inflate tremendously.
•  The initial expansion was faster than the speed of light.
I. Formation of the Universe
III. Formation of Galaxies
1. Galaxies began as a clouds of gas and dust (also
called a nebulae)
2. The clouds collapsed under the force of their
own gravity, forming galaxies of a variety of
shapes.
III. Formation of Galaxies
3. Our galaxy the Milky Way is a barred
spiral galaxy, consisting of a nucleus
surrounded by arms that rotate in a clockwise
direction.
Our solar system is here
4. Solar systems similar to ours move around
in this galaxy in a regular pattern.
IV. Shape of Galaxies
1. Sa Barred-Spiral (like the Milky Way--OUR
galaxy). See background picture.
2. Spiral
… some are SBb Barred
Spirals
3. Irregular and others
2. Elliptical