Transcript 3OriginoftheUniverseandSS

Origins of the Universe
and Solar System
From Universe to Galaxy to Solar System
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!
•
The sphere “exploded”, forming a gigantic, hot expanding cloud
•
As the cloud moved, parts condensed and formed
billions of galaxies
•
The galaxies continue to move outward today
•
Most commonly accepted theory of universe formation
I. Formation of the Universe
PREVIOUS IDEAS:
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 (no big bang) and has no end
RECENT DEVELOPMENTS:
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.
• Also works with the concept of a Multiverse--our observable
universe is just one of many “parallel” universes that inflate in and
out of existence!
II. Evidence for Big Bang/Inflation
1. In 1965, Panzias And Wilson
discovered background radiation
interfering with radio antennae,
causing a hiss in phone lines.
•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 your television is made up of a small
percent of radiation from the formation of the universe!)
2. Astronomers observe “red shifts” throughout the universe.
•This redness is the result of light being stretched as objects in the
universe move away from each other (the result of the big bang).
III. Formation of Galaxies
1. Galaxies begin as a spherical cloud (also called a nebula) in space.
2. The cloud collapses under the force of it’s own gravity, forming galaxies of a
variety of shapes.
Our solar system is here
3. Our galaxy the Milky Way is a spiral galaxy, consisting of a nucleus surrounded
by arms that rotate in a clockwise fashion.
4. Solar systems similar to ours move around in this galaxy in a regular pattern.
IV. Shape of Galaxies
1. Spiral (like the Milky Way--OUR galaxy). See
background picture.
QuickTime™ and a
decompressor
are needed to see this picture.
… some are Barred Spirals
Our solar system is here
2. Elliptical
QuickTime™ and a
decompressor
are needed to see this picture.
3. Irregular and others
QuickTime™ and a
decompressor
are needed to see this picture.
V. Formation of a Solar System
•Within each galaxy are many nebulae (plural of nebula).
•A nebula is a cloud of interstellar dust and gas from which stars and
eventually solar systems are formed.
•Nebula can be many colors depending on the chemical makeup of the
gas.
How a Nebula becomes a
Solar System - The Solar
Nebula Hypothesis:
Just as an ice-skater’s spin
speeds up when she pulls her
arms in, so does a cloud of
dust in space. As the cloud
spins faster, enough pressure
is created to produce fusion
in the center of the disk,
forming a star like our sun.
Planets are formed from the
rings left behind as the dust
disk formed.
VI. Formation of OUR solar system:
•Our sun was the center of that cloud of
dust and gas.
•As the planets formed, the more dense
ones were pulled closest to the sun. They
are called Terrestrial Planets (Mercury,
Venus, Earth, and Mars).
•The less dense planets moved toward the
outer portion of the solar system. They are
called Jovian Planets, or Gas Giants.
(Jupiter, Saturn, Uranus, and Neptune)
•Pluto is now thought to be a minor planet,
most likely a captured comet who was
drawn in by the gravity of the sun and
placed in an orbit around it (similar to
asteroids)
More about the planets and moon later!