astronomy intro
Post on 11-May-2015
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Astronomy
To Infinity and Beyond!
What’s in the Universe?
Everything –
All matter and energy that exists now, in the past and in the future
Is Every Light in the Sky a Star?
Every spot of light here is another galaxy!
Andromeda Galaxy
What’s in a galaxy?
Nebula
How Far is Far?• Too far to measure with meters
or kilometers• How about a light-year?• Nearest galaxy is _______ light-
years away160,000
• What we see happened in the past
How Did it All Begin?
•How old is the universe?•What was there before the universe was created?
•What is the evidence?
Edwin Hubble•Measured movement of
galaxies•Found that all galaxies were
moving away from each other•VERY unexpected•Galaxies farther away moving
faster
Big Bang Theory The dominant scientific theory of the
origin of the universe.
Big Bang – The Theory
• The universe was once extremely dense
• A cosmic explosion occurred ~ 13-15 billion years ago
• Right after the explosion matter in the universe was very hot and dense
• The universe has been expanding and cooling since then
What Happened Next?• At first, the universe was so hot and
dense that matter was very different• Temperatures exceeded billions of
degrees• As the universe expanded and
cooled, particles that make up atoms, like quarks and electrons, formed
Cosmic Background Radiation
• In 1965 dim radiation was found coming from apparently empty parts of the universe
• Like long-lasting embers from a fire
Other Theories
•Cycles of expansion & contraction
•Steady State
How Old?
•Calculate backwards using velocities of galaxies
•13-15 billion years
What Happens Next?There are possibilities….
•If the amount of matter in the universe is enough……
•If not ……………
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