The Universe

How do we know what happened billions of years ago? Scientific theories are usually formed when someone makes observations and then forms conclusions about what he/she sees.

What’s happening? (observe) The kitchen is messy with spilled flour and sugar, the oven is warm, candles are scattered around the floor.

Form a conclusion Someone is making a birthday cake

Detectives are Scientists They make observations about: –Evidence at the scene –Prints left behind –Motive or reasons –DNA collected

…and form conclusions. They may not have witnessed the crime, but they can make an educated guess about what happened.

Which direction did the blast from Mt. St. Helens, WA come from?

Which way does the wind usually blow on Humphrey Head Island, UK?

You weren’t there, but you can make an educated guess based on your observations. Which direction is the bullet moving? To the left? To the right?

Astronomers (people who study space) are detectives They study and observe the universe and then form conclusions about out how it probably formed.

So how did our universe form? Using telescopes, spectroscopes, and other instruments, scientists have made the following observations….

Observations What is happening to our universe? Years ago Present day

Galaxies are spreading farther and farther apart If we work backwards, then 13.7 billion years ago, all matter use to be all together

How do we know if stars are moving towards Earth or away? The Doppler effect Chime demo Sound waves move differently when they come towards you or move away from you. Doppler effect siren eature=related Doppler effect car horn

Light waves from stars also show a difference when they move. Use a spectroscope Red shift = moving away from you Blue shift = moving towards you

What is the star doing? Moving away from you. Moving towards you.

Astronomers use these observations to conclude that the whole universe must have been all together at one point about 13.7 billion years ago.

The Big Bang! - A well supported scientific theory which explains the beginnings of our universe

billion years ago, all matter (stuff you can touch) was together in a very small ball, then it exploded. Parts of atoms floated around the universe.

2.One billion years later, atoms formed and large clouds of hydrogen (H) and helium (He) were pulled together due to gravity and galaxies formed.

3. H and He crashed into each other creating light and heat (through nuclear reactions) and stars formed.

4. Other heavier elements came together to form planets and moons

Stars, planets, and moons continue to form now throughout the universe.

So what will happen to our universe?

5. Most astronomers think the universe will continue to expand indefinitely.

Think about the universe being like a balloon-spots on the balloon get farther and farther apart as it expands

OR…… ???

5. The universe will stop expanding and gravity will pull it back into a ball and then the big bang will happen again.

History Channel Big Bang 3min The Big Bang demonstrated by a college band How big is the Universe? Big Bang Theme Song

We are star stuff -Carl Sagan

Homework Create a five panel comic strip that shows the five steps (1-5 on your notes) of the formation of our universe. Each panel should be colored in and have a brief sentence about what happened. You may chose either ending to give to panel five.