This document provides an overview of astronomy and the origins and structure of the universe. It discusses that the universe contains all matter and energy that exists now and ever will exist. It also notes that every spot of light in the sky is another galaxy, with the Andromeda Galaxy being the nearest at around 2.5 million light years away. The document then summarizes the Big Bang theory, which postulates that the universe began in an extremely dense and hot state around 13-15 billion years ago and has been expanding and cooling ever since.

1. Astronomy
Buzz_Lightyear
To Infinity and Beyond!

2. What’s in the Universe?
Everything –
All matter and energy that exists now,
in the past and in the future

3. Is Every Light in the Sky
a Star?
Every spot of light here is
another galaxy!

4. Andromeda Galaxy
What’s in a galaxy?

5. Nebula

6. How Far is Far?
• Too far to measure with meters or
kilometers
• How about a light-year?
160,000
• Nearest galaxy is _______ light-
years away
• What we see happened
in the past

7. How Did it All Begin?
• How old is the universe?
• What was there before the
universe was created?
• What is the evidence?

8. Edwin Hubble
• Measured movement of galaxies
• Found that all galaxies were
moving away from each other
• VERY unexpected
• Galaxies farther away moving
faster

9. Big Bang Theory
The dominant scientific theory of the origin
of the universe.

10. 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

11. 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

12. Cosmic Background Radiation
• In 1965 dim radiation was found
coming from apparently empty parts of
the universe
• Like long-lasting embers from a fire

14. Other Theories
• Cycles of expansion &
contraction
• Steady State

15. How Old?
• Calculate backwards using
velocities of galaxies
• 13-15 billion years

16. What Happens Next?
There are possibilities….
• If the amount of matter in the
universe is enough……
• If not ……………