1. A billowing tower of gas and dust rises from the stellar nursery known as the Eagle Nebula. This small piece of the Eagle Nebula is 57 trillion miles long (91.7 trillion km)

2. Optics

3. The Crab Nebula is a supernova remnant, all that remains of a tremendous stellar explosion. Observers in China and Japan recorded the supernova nearly 1,000 years ago, in 1054

4. Intricate structures of concentric gas shells, jets of high-speed gas and shock-induced knots of gas make up this complicated planetary nebula. The Cat's Eye Nebula is about 1,000 years old, and could have resulted from a double-star system

5. Hubble Space Telescope

8. And from the very large…

9. Amoeba

11. Paramecium

13. H1N1 Influenza virus (approx 100nm)

14. 4.1 Producing Light
Light is emitted from matter by electrons that have absorbed energy to become ‘excited’, then the electrons release back some of the extra energy as light.

15. Light Emission
Source of Energy Absorbed
Sunlight
Nuclear fusion which produces enough heat to excite electrons

16. Source of Energy Absorbed
Light Emission
Source of Energy Absorbed
Incandescence
eg. Light bulb with a
filament
Electricity which makes the filament hot enough to excite electrons – unfortunately only 5% efficient.

17. Eg. LED lights & neon signs
Light Emission
Source of Energy Absorbed
Electric Discharge
Eg. LED lights & neon signs
Electricity which directly excites the electrons

18. Source of Energy Absorbed
Light Emission
Source of Energy Absorbed
Fluorescence
eg. fluorescent bulbs
Electricity that excites the electrons to emit UV radiation, which in turn excites the electrons in the white powder coating inside the bulbs.

19. Source of Energy Absorbed
Light Emission
Source of Energy Absorbed
Phosphorescence
eg. Glow in the
dark stickers
UV radiation excites electrons that slowly release their energy, which gives its longer-lasting effects

20. Light Emission
Source of Energy Absorbed
Chemiluminescence
eg. Glow sticks
Chemical reactions in which electrons of the products release energy.

21. Source of Energy Absorbed
Light Emission
Source of Energy Absorbed
Bioluminescence
eg. fireflies
Like chemiluminescence, but reactions in living cells