Origins of the Universe

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TITLE
•Notes will go here
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•Bulleted or outlined
information works best
-Try not to use long
sentences
-Avoid paragraphs
•Use abbreviations YOU
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A helpful guide...
FOR THESE NOTES ONLY...
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
Universe
Big ideas or
topics are at the
top. These
should be your
sub-headings,
with your bullets
following below
Cosmology
•
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
Began
•
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
down.
Steady State
Theory
•
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
ride
The Big Bang
Model
•
•
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
notes.
•
•
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
Theories
•
Many observational tests can be done to provide
support for all theories
•
Today, evidence weighs in favor of the Big Bang
Theory
B.B.T. - Present
Day
•
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
perspective.
•
Journey to the Big Bang
Credit: NASA / WMAP Science Team
Hubble image: NASA and ESA
Formation of Our
Galaxy
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
out
BUT they can condense because of gravity
•
Eventually becomes stars and possibly
planets
Collapse of the
Cloud
•
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
accumulate
•
These began to merge together to make larger
ones
•
Eventually became hundreds of kilometers in
diameter
•
Called planetesimals
Planetesimals
•
Continued to grow and merge with others
•
Merges were violent
•
•
Sometimes planetesimals were destroyed
Overall result was a small number of large bodies
(planets)
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
material
Asteroid Belt
•
Actually just planetesimals that never merged
•
Stayed between Mars and Jupiter
•
•
Jupiter’s gravitational force prevented them from
merging.
Asteroid - rocky remnant of the early system
•
A few kilometers to 1000 kilometers in diameter
Meteoroid, Meteor,
Meteorite
•
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.
Comets
• 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
(AU))
• 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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