Origins of the Universe

Cornell Notes...
•This column
gets filled out
•Can be key
about notes
-used as
questions for
•Can also be
about things
you did not
•Notes will go here
-from my PowerPoints
•Bulleted or outlined
information works best
-Try not to use long
-Avoid paragraphs
•Use abbreviations YOU
A helpful guide...
I’m going to include some helpful
hints on how I organize my notes.
They will be in small boxes off to the
side, in bright blue font.
Don’t write those things down.
Credit: NASA / WMAP Science Team
Formation of the
Big ideas or
topics are at the
top. These
should be your
with your bullets
following below
The study of the universe
Its current nature
Its origin and evolution
Key vocabulary is
bolded and
underlined. These are
very important!
The Universe
Universe is expanding
Which means it had to have a beginning.
How the Universe
Theories of how the universe began:
Steady State Theory
Big Bang Theory
Inflationary Model
Usually when I give you
lists like this, we will
discuss each of them in
class. You probably do
NOT need to write
anything but the title
Steady State
Proposes that the universe looks the same on large
scales, and has always looked that way
Universe does not change with time
BUT! If the universe is expanding, how can this
be true?
New matter is created and added to the universe as
it expands
The italicized question
does NOT need to be
written down. It’s just
something to think about.
Big Bang Theory
NOT an explosion into space
IS an expansion of space with matter along for the
The Big Bang
Consists of a competition between:
Outward momentum of expansion
Inward force of gravity
This is how the universe acts to slow the expansion
B.B.T. - Outcomes
of Expansion
Three outcomes for the universe: If there is information
written under each
• Open Universe
bullet in a list, then
this is info you should
• Expansion never stops
probably have in your
• Closed Universe
Expansion will stop and turn into contraction
Flat Universe:
Expansion will slow to a halt in an infinite
amount of time, but never contract
Inflationary Model
Version of the Big Bang Model
Universe began as a fluctuation in a vacuum
Expanded very rapidly for a fraction of a second
Settled into a more orderly expansion
Research of
Many observational tests can be done to provide
support for all theories
Today, evidence weighs in favor of the Big Bang
B.B.T. - Present
Appears that the rate of expansion slowed for
awhile, but is now gathering speed
What is causing this?
Some scientists suggest it is caused by an
unknown force
Stronger than gravity
Pushing galaxies apart
Looking Back
A trip through space and time to put the B.B.T. in
Journey to the Big Bang
Credit: NASA / WMAP Science Team
Hubble image: NASA and ESA
Formation of Our
Stars and Planets
Formed from interstellar clouds
Clouds of dust and gas
Mostly hydrogen and helium gas
Many interstellar clouds are observed along the
Milky Way
Have low density
This means their materials are very spread
BUT they can condense because of gravity
Eventually becomes stars and possibly
Collapse of the
Very slow at first
Speeds up and starts rotating as it collapses
Becomes a rotating disk (solar nebula)
Center of the disk (densest part) eventually
becomes the Sun
As the disk cooled, different elements were able to
form in solid and liquid states
Growth of Objects
As condensing slowed, small particles started to
These began to merge together to make larger
Eventually became hundreds of kilometers in
Called planetesimals
Continued to grow and merge with others
Merges were violent
Sometimes planetesimals were destroyed
Overall result was a small number of large bodies
The Planets
Jupiter formed first
Continued to grow
Saturn was next
Then the other gas planets
None of the planets could get as big as Jupiter
because it already had so much of the galaxy’s
Asteroid Belt
Actually just planetesimals that never merged
Stayed between Mars and Jupiter
Jupiter’s gravitational force prevented them from
Asteroid - rocky remnant of the early system
A few kilometers to 1000 kilometers in diameter
Meteoroid, Meteor,
Meteoroid - any interplanetary object that falls and
enters Earth’s atmosphere
Meteor - a meteoroid that burns and produced a
streak of light.
Meteorite - a meteoroid that does not burn up
completely and part of it hits the ground.
• Small bodies with highly eccentric orbits around the Sun
• Made of ice and rock
• 1-10 km in diameter
• Two major clusters of comets:
• Kuiper Belt - close to Pluto (30-50 Astronomical Units
• 1 AU = 149,600,000 km
• Oort Cloud - 100,000 AU from the Sun
Comets (continued)
• When we see comets, it’s because they are within 3 AU
of the Sun
• Start of evaporate, forming a head and tail
• Hale Bopp - last seen in 1997 - will be seen again
in 4397
• Periodic Comets - those that repeatedly orbit into the
inner solar system
• Halley’s Comet - last seen in 1985-86 - will be seen
again in 2061 - has a 76 year period
Meteor Shower
When Earth intersects a cometary orbit

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