1. Stars, starlight
AND
The
Big Bang

2. OUTCOME QUESTION(S): S1-4-07:
What is the evidence for the Big Bang Theory?
Vocabulary & Concepts 
Electromagnetic spectrum Doppler Effect
Red Shift Big Bang Astronomy
Cosmology

3. Light /heat are types of Electromagnetic Energy
Star light can be used to determine temperature, composition and size (mass)
Light /heat are types of Electromagnetic Energy
Hot objects (like stars) radiate different types of energies too – as temperature changes so does the main energy released

4. Electromagnetic Spectrum of Energies
HEAT
Low energy High energy
Because of the shape of the waves, the colours always separate into this same organized pattern
ROY G BIV
This is why other telescopes and tools are needed – we can only access a small amount of informational energy from stars
Red light is low energy – cool
Blue is high energy - hot

5. Red-Shift and the Big Bang
There is evidence that the universe is expanding:
- Red-shift of light from stars and galaxies
- Cosmic Microwave Background Radiation
- Gravitational waves (new)
1. Light waves work exactly like any other wave:
Waves can be far apart - long wavelength
Waves can be close together - short wavelength
We’re going to focus on the oldest, and simplest – “red-shift”
Long wavelegth
Short wavelength

6. 2. Waves are also affected by motion.
Noticeable effect is called the Doppler Effect
You have experienced this effect with sound waves
Moving – compressed in front, spread out in back
Stationary:
all waves move outward evenly

7. Higher pitch Lower pitch Doppler effect: Sound waves
You brain hears the distorted wave pattern as a different sound then is really being made by the ambulance

8. Bluer colour Redder colour Doppler effect: Light waves
You brain sees the distorted wave pattern as a different colour then is really being made by the object

9. a compressed green light appears more blue
“blue shift”
a s t r e t c h e d green light appears more red
“red shift”
Your eyes don’t know what colour it “should” be, it can only interpret the waves it sees – it can’t tell the difference between “red” and “s t r e t c h e d green”

10. 3. Spectra of ALL stars / galaxies show red shift.
Far away galaxies show more red shift - faster
Evidence that the universe is expanding and speeding up too – think of it as the first half of an explosion
“red shift” spectra
“blue shift” spectra
Normal spectra

11. The universe is expanding:
Must have started out from one point – singularity
Reverse the explosion – the Universe must have started from a packed, dense mass of material under pressure
Big Bang
Rapid expansion of Universe from the singularity
Evidence suggests Universe is 14 billion years old
Scientists cannot yet explain all “how” or “why”
Not the only explanation of the universe origin
BUT beliefs are not theories – only scientific theories can be tested and proven

12. Astronomy – study of all objects in the universe.
Cosmology – study of the origin of the universe.

13. CAN YOU ANSWER THESE QUESTIONS? S1-4-07:
What is the evidence for the Big Bang Theory?
Vocabulary & Concepts 
Electromagnetic spectrum Doppler Effect
Red Shift Big Bang Astronomy
Cosmology