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 ……………